2019年高考英语 语法必考考点（12）状语从句（含解析）.doc

2019年高考英语语法必考考点（12）：状语从句含解析【考点解读】在复合句中，修饰主句或主句谓语的句子叫作状语从句。状语从句可位于主句之前，也可位于主句之后。状语从句可分为时间、地点、原因、结果、条件、方式、让步、比较和目的等九大类。一、状语从句引导词列表从句类型从属连词时间状语从句as, after, before, once, since, till, until, when, whenever, while, as soon as地点状语从句where, wherever, anywhere, everywhere原因状语从句because, since, as, now (that), seeing that, considering that, in that结果状语从句that, so that, so/such .that .目的状语从句so that, in order that, for fear that, in case, for the purpose that条件状语从句if, unless, as/so long as, on condition that, in case, provided that比较状语从句than, as .as, not so/as .as方式状语从句as, as if/though, how让步状语从句though, although, even if/though, however, whatever, as, while【点睛】(1)上述有些连词除了能引导状语从句外，还可引导定语从句和名词性从句。在使用的时候，要根据句子结构和句意来判别和区分不同的从句，正确使用引导词。以where为例，试比较下列多种从句的区别。You are to find it where you left it. (地点状语从句)Tell me the address where he lives. (定语从句，先行词为the address)I dont know where he came from. (宾语从句)Where he has gone is not known yet. (主语从句)This place is where they once hid. (表语从句)(2)在两个分句间要有一个且只有一个连词，千万不能按汉语习惯。Because he was ill, he didnt e to school. He was ill, so he didnt e to school.(3)在时间、地点、条件、方式或让步状语从句中，若从句的主语与主句的主语一致(或从句的主语为it)，从句的谓语又包含动词be时，从句中的“主语be”部分可省略。When (he was) asked about it, he kept silent.Fill in the blanks with articles when (they are) necessary.If (it is) possible, Ill explain it again later.She stood at the gate as if (she was) waiting for someone.二、时间状语从句1. “一就”的表达如下表词类常用词例句从属连词as soon asHe started as soon as he received the news.副词immediately, directly, instantlyThey phoned immediately they reached home.名词/名词短语the minute/moment/second/instant, every/each timeThey ran away the moment they saw the guard.Each time I was in trouble, he would stand by.句型结构no sooner .than ., hardly/scarcely .when .No sooner had I arrived home than it began to rain.2. till和until的用法(1)肯定句中，主句谓语动词必须是延续性动词，意为“某一动作一直延续到某时间点才停止”。He remained there till/until she arrived.(2)否定句中，主句谓语动词必须是非延续性动词，从句为肯定式，意为“某动作直到某时间才开始”。I was not aware that I forgot my ticket till/until I got to the station.(3)till不可置于句首，until可以。(4)强调和倒装句中，not .until应视为一个整体，同时被强调或置于句首。It was not until you told me that I had any idea of it.Not until you told me did I have any idea of it.3. before和since的用法(1)before常用于表示“还未就；不到就；才；趁；还没来得及”等含义。We had sailed four days and four nights before we saw land.He rushed out of the house before I could say anything else.(2)句型It was/will be时间段before .意为“过了多久才”。It was not long before . /It will not be long before .意为“不久就”。It will be one year and a half before I e back.It was not long before he sensed the danger of the position.(3)since从句的谓语动词一般是短暂性动词，主句谓语动词则是延续性动词或反复发生的动作。since引导的从句时态为一般过去时，主句时态为现在完成时或现在完成进行时。She has been working for the pany since she left school.(4)句型It is/has been时间段since .意为“自从到现在多久了”。It is a long time since I saw you last time. I have not seen you for a long time.It has been two years since I was admitted to this key middle school. I was admitted to this key middle school two years ago.It is three years since I smoked a cigar. It is three years since I stopped smoking a cigar.三、原因状语从句1. because, as, since, now that的用法区别如下表：引导词位置内涵语气能否回答why能否强调because主句前或后直接原因强能能as主句前或后已知原因弱不能不能since/now that主句前Why are you absent from the meeting? Because I am ill.He is disappointed because he didnt get the position.As his mother was a great music lover, he lived with music from birth.Since his music style was new, he decided his hairstyle had to be new too!2. 除了状语从句外，一些介词短语也可以表示原因。如：because of, thanks to, due to, owing to, on account of等。They were late because of the traffic.3. for引导表示原因的并列句，补充说明根据什么推断出前一分句的结果。He must have gone to bed, for the light is out.四、地点状语从句注意地点状语从句与定语从句的区别，试比较：This is the place where we used to live a few years ago.Lets go where we can find a better job.五、目的状语从句与结果状语从句1. so that引导的目的状语从句及结果状语从句的区别：(1)so that引导目的状语从句时，只能置于主句之后，从句谓语部分常需用情态动词can, may, could等，可用in order that代替。后者更正式，引导的状语从句可置于主句前或后。(2)so that引导结果状语从句时，从句的谓语部分一般没有情态动词，其作用等于so。试比较：We got up early so that we could catch the train. (此句只强调早起的目的，结果未明)We got up early so that we caught the train. (此句表明了早起的结果：赶上了火车)2. so .that与such .that引导结果状语从句的区别：其规律由so与such的不同词性决定。such是形容词，修饰名词或名词词组，so是副词，只能修饰形容词或副词。常见以下几种句型结构：(1)so形容词/副词that从句。He was so excited that he could not say a word.(2)sucha/an形容词单数可数名词that从句。Its such a good chance that we must not miss it.(3)such形容词复数名词/不可数名词that从句。It was such fine weather that we went out for a walk.(4)so形容词a/an可数名词单数形式that从句。试比较：Mike is such an honest worker that we all believe him. Mike is so honest a worker that we all believe him.(5)somany/much/few/little名词that从句。在“两多两少”(many/much/few/little)前要用so来修饰。He earned so little money that he couldnt support himself.3. 除了状语从句外，不定式in order to/so as to等也可以表示目的。In order to get home earlier, we had to run all the way.4. 除了状语从句外，too .to, enough .to, so . as to, such (.) to等不定式结构也可以表示结果。We got up early enough to catch the train.六、条件状语从句1. 条件状语从句分真实性(有可能实现的事情)与非真实性(条件与事实相反或者在说话者看来不大可能实现的事情)条件句。后者应使用虚拟语气，试比较：If you work hard, youll make progress. (真实条件句)If you had worked harder, you would have passed the exam. (虚拟条件句)2. “祈使句and .”和“祈使句or/otherwise .”以上两种结构中的祈使句都表示条件， and或or/otherwise后面的内容表示结果。Climb to the top of the mountain and youll see the whole city. If you climb to the top of the mountain, youll see the whole city.Hurry up, or/otherwise youll be late. If you dont hurry up, youll be late.3. “名词and .”结构此结构中的名词可改为if引导的条件状语从句，有时也可改为由when, after引导的时间状语从句， and后面的句子表示主句内容。Another sound and the enemy would discover us. If we made another sound, the enemy would discover us.A few minutes and they went away. When/After a few minutes had passed, they went away.七、让步状语从句1. as引导让步状语从句时，需要使用倒装结构，表示强调。被强调的部分可为名词、形容词、副词等。若名词提前，要求省略冠词。Tired as he was (Though he was tired), he continued his work.Much as I respect him (Though I respect him much), I cant agree to his proposal.Child as he is (Although he is a child), he could raise a stone of 100 kilos.2. while引导让步状语从句，一般放在句首。While (Although) I dont like it, I will try to learn it well.3. 注意“no matter疑问词”引导的让步状语从句。No matter how hard (However hard) I have tried, I cant find the answer.八、比较状语从句注意两种特殊的比较状语从句结构：1. the more .the more结构。The more you exercise, the healthier you will be.2. A is to B what/as X is to Y结构。Food is to men what oil is to machines.九、方式状语从句1. 方式状语从句表示动作的方式。as之前常可用just加强语气。When in Rome, do as the Romans do.I did just as the teacher did.2. as if/as though引导方式状语从句时，常用虚拟语气。He talks as if he knew everything in the world.She spoke English so well as if she had been to America.状语从句是高考英语的一个十分重要的考点，几乎每年都考。综观历年高考英语试题以及近年来各省市试题，我们发现高考对状语从句的考查主要涉及引导状语从句的从属连词的用法与辨析。由于高考对状语从句的考查主要涉及引导状语从句的从属连词的用法与辨析，所以在做状语从句考题时，考生在特别注意以下几点：(1) 要弄清状语从句的几个主要类别：如时间状语从句、条件状语从句、原因状语从句、地点状语从句、目的状语从句、结果状语从句、让步状语从句等，同时弄清它们相应的主要“引导词”及其相关意义。(2) 学会用语境分析法解题：综观历年高考英语状语从句考题，至少有90%的考题可通过分析语境来解决。具体做法是，将四个选项分别放入题干中，意思最明确，逻辑最通顺，最合情合理的，就一定是最佳答案。(3) 留意某些含有状语从句的特殊句式：如it issince，notuntil，hardlywhen，no soonerthan等。(4) 排除命题干扰：有时命题者为了增加试题的难度和灵活性，可能会在题干中增加干扰成分，如增加修饰语或插入独立结构或插入语，使用省略结构或省略句式等，同学们在做题时要注意排除这些干扰。【真题分析】一、单项选择1. (2018江苏卷) _ youcansleepwell,youwilllosetheabilitytofocus,planandstay motivatedafter one ortwonights.A. Once B. Unless C. If D. When【答案】B【解析】考查状语从句。句意：除非你睡得好，否则一两个晚上之后，你会失去专注、计划和保持动力的能力。A. Once一旦；B. Unless除非；C. If如果；D. When当时候。故选B。2. (2018天津卷) Lets not pick these peaches until this weekend _they get sweet enough to be eaten.A. ever since B. as if C. even though D. so that【答案】D【解析】考查状语从句。句意:让我们这个周末再摘这些桃子，这样的话，它们吃起来就变得足够的甜。A. ever since自那时起；B. as if好像；C. even though尽管；D. so that以便。从句为目的状语从句，用 so that引导，故选D 3. (2018北京卷) _ we dont stop climate change, many animals and plants in the world will be gone.A. Although B. While C. If D. Until【答案】C4. (2017北京卷) If you dont understand something, you may research, study, and talk to other people _ you figure it out.A. because B. though C. until D. since【答案】C【解析】考查状语从句。A. because因为B. though尽管C. until直到D. since自从。句意：如果你无法理解某个东西，你可能会去研究，学习和他人探讨直到你解决为止。根据句意可知选用umtil直到，选C。5.【2017北京】25. _ birds use their feathers for flight, some of their feathers are for other purposes.A. Once B. If C. Although D. Because【答案】C【解析】考查状语从句。A. Once一旦 B. If如果 C. Although尽管 D. Because因为。句意：尽管鸟儿们用羽毛来飞翔，但是他们的一些羽毛还有其他用途。根据语境可知前后之间是让步关系，故选C。6. (2017江苏卷) Located _ the Belt meets the Road, Jiangsu will contribute more to the Belt and Road construction.A. why B. when C. which D. where【答案】D【解析】考查状语从句。be located in+地点名词,位于坐落某地, where引导的地点状语从句在此相当于 in some place，故选D。句意：位于丝绸之路交汇处的江苏省将会对“一带一路”的建设做出更大的贡7. (2016北京卷) My grandfather still plays tennis now and then, _ hes in his nineties.A. as long as B. as if C. even though D. in case【答案】C【解析】考查状语从句。句意：即使是九十多岁了，我的爷爷仍然时不时地打打网球。A.as long as只要，引导条件句；B.as if似乎，引导方式状语从句或表语从句；C. even though即使，引导让步状语从句；D.in case以防，引导目的状语从句。这里是转折关系，故选C。8. (2016浙江卷) _online shopping has changed our life, not all of its effects have been positive.A. Since B. After C. While D. Unless【答案】C9. (2016北京卷) I really enjoy listening to music _ it helps me relax and takes my mind away from other cares of the day.A. because B. beforeC. unless D. until【答案】A【解析】考查状语从句。句意：我非常喜欢听音乐，因为它能让我放松，使我不去想其它的事。前后是因果关系，故选A。10. (2015北京卷) _the damage is done, it will take many years for the farmland to recover.A. Until B. Unless C. Once D. Although【答案】C【解析】考查状语从句。句意：一旦农田被毁坏，将需要许多年的时间才能得以恢复。A. until译为到为止，直到才，在以前；B. unless译为如果不，除非；C. once译为一旦，一经便；D. although译为虽然，然而，尽管。结合句意，故选C。二、单句填空1. (2018新课标I卷) While running regularly can make you live forever, the review says it is more effective at lengthening life _walking ,cycling or swimming.【答案】than【解析】考查连词。句中it指代running, 空后是walking,都是动名词，再根据句意：虽然经常跑步不能使你永远活着，但是评论说经常跑步在延长生命这方面比步行更有效，故填连词than。2. (2018新课标II卷) Corn uses less water _rice and creates less fertilizer(化肥) runoff.【答案】than3. (2017浙江卷) Pahlsson screamed 58 loudly that her daughter came running from the house【答案】so【解析】考查状语从句。 Pahlsson的尖叫声是如此响亮以至于她的女儿从房子中跑了出来。此处是sothat结构，表示“如此以至于”。4. (2016新课标III卷) 0ver time, 65 the population grew, people began cutting food into small pieces so it would cook more quickly【答案】as或when 【解析】考查状语从句。随着人口的增长或当人口增长时，人们开始把食物切成小片。根据句意和句子结构可知，空处引导状语从句，表示“随着”或“当时”，故填as或when。5. (2016四川卷) 66 it cried，she rocked it back and forth and gave it little forting pats.【答案】When/If【解析】考查连词。当熊猫宝宝哭泣的时候如果熊猫宝宝哭泣，熊猫妈妈会前后摇晃熊猫宝宝，而且会轻轻地拍它。语境表明，此处用连词When或If引导状语从句。6. (2015湖南卷) Its simpler because, 48 you have a puter, you can find information you need by searching the Internet.【答案】if【解析】考查从属连词。根据句子结构和句意可知，此处应填条件状语从句的引导词if，意为“如果”。7. (2015广东卷) 0ne day, the cow was eating grass 20 it began to rain heavily.【答案】when【解析】考查连词。有一天，牛正在吃草，突然天开始下大雨。根据语境可知，此处应用when“正在这时（突然）”。8. (2014辽宁卷) 69 you dont mind，Ill stop and take a deep breath【答案】if【解析】考查状语从句。分析句子结构可知，空处引导条件状语从句，所以应用if。9. (2013湖南卷) 48 the areas used for playing fields are often rough and rocky, millions of real balls go flat (变瘪) in 24 hours,【答案】Because10. (2012广东卷) 5 he thought he could escape attention by sitting at the back，he was wrong.【答案】If【解析】考查状语从句。此处表示假设，故用If（如果）引导条件状语从句。三、单句改错1. (2015陕西卷) My only mistake was that I dropped some on the floor after I was packing them up.【答案】afterwhen/while【解析】考查状语从句。句意：当我在把它们打包起来时, 一些（饼干）掉到了地板上。表示“当的时候”, 要用when或while。2. (2015浙江卷) If I was only a child when I studied in that classroom, I will never forget it.【答案】IfAlthough/Though【解析】考查连词。此处意为“虽然”, 应用Although或Though来引导让步状语从句。3. (2014四川卷) If you notice that when someone is missing and hurt, tell your teacher immediately.【答案】去掉when【解析】考查句子结构。此处表示“如果你注意到有人失踪了或是受伤了”。根据句子的结构来判断, notice后接一个宾语从句, 从句表达完整的内容, 故去掉when。4. (2013陕西卷) As soon as we arrived, so we dropped the lines into the water.【答案】去掉we前的so【解析】考查连词。上文有as soon as引导时间状语从句, 故so多余。【对点测试】一、单项选择1. (2018天津市耀华中学) Opposite is St. Pauls church, _you can hear some lovely music.A. which B. that C. when D. where【答案】D2. (2018天津市耀华中学) Simon thought his puter was broken _ his little brother pointed out that he had forgotten to turn it on.A. until B. because C. while D. though【答案】A【解析】考查状语从句。句意：Simon在他弟弟告诉他忘了开机之前，一直以为电脑坏了。Notuntil意为“直到才”，故选A。3. (2018江苏97校联考) How do you like the advertisement of the way to losing weight?Dont fall for it. In the beginning, that may do, but after a while you will end up back _ you started.A. as if B. where C. even if D. when【答案】B【解析】考查连词。A. as if好像；B. where在的地方；C. even if即使；D. when当时。句意：你觉得这个减肥方法的广告怎么样? 不要信以为真。开始的时候，可能会这样，但是很快你就会回到原来的样子。此处开始的地方指原来的样子，故选B.4. (2018天津市南开中学) _he once felt like giving up, he now has the determination to push further and keep on going.A. Where B. As C. In case D. Now that【答案】A【解析】考查状语从句。句意：曾经让他感到想放弃的地方，现在他决心继续前进。A那里；B尽管，当，因为，随着；C以防；D既然。where表示地点，引导让步状语从句；as引导让步状语从句常用倒装，即tried as he has；in case表目的；now that表原因。这里指让他感到想放弃的地方，故选A。 5. (2018天津市河东区) My mother is always warning me when I go out, “Dont get off the bus it is stopping.”A. until B. while C. before D. after【答案】B【解析】考查时间状语从句。句意：我出去的时候，妈妈总是警告我：“不要在车停的时候下车。” 此处while意为当的时候，也可以说Dont get off the bus until/before it stops. 故选B。6. (2018北京市海淀区) You dont need an invitation to help others. Give help _you are asked.A. if B. as C. though D. before【答案】D7. (2018北京市丰台区) Someone called me up at midnight, but he had hung up I could answer the phone.A. as B. since C. until D. before【答案】D【解析】考查状语从句。句意：有人在半夜给我打电话，但我还没来得及接电话，他就挂断了电话。before与情态动词can/could连用，表示“还没来得及就”，故此处用before引导时间状语从句，故答案为D。8. (2018北京市朝阳区) Sometimes tests are needed _ doctors discover exactly whats wrong with your body.A. since B. before C. although D. if【答案】B【解析】考查连词。A. since 因为，由于；B. before在之前；C. although虽然，尽管；D. if如果。句意：有时在医生准确发现你的身体出了什么问题之前做检查是必要的。根据前后句的关系，我们可以判断出检查应在医生诊断之前，故选B. 9. (2018天津市南开区) Work _ they might, they didnt get the result they expected.A. although B. since C. as D. as though【答案】C【解析】句意：尽管他们努力工作，但是仍然没有获得期望的结果。本题考查as引导的状语从句倒装的情况(倒装句是一常见的语言现象，要引起大家的足够的重视)。as意为“尽管” 时引导让步状语从句，把动词放在as之前。10. (2018江苏泰州中学) The countrys chief exports are coal, cars and cotton goods, cars_ the most important of these.A. have been B. are C. being D. are being【答案】C【解析】考查独立主格结构。英语中两个简单句之间一般不能只用“，”隔开。此句中，分词结构being the most important of these有自己的逻辑主语，即cars，此部分在主句中充当状语，起到对主句进行补充说明的作用。句意：该国的主要出口产品是煤、汽车和棉花制品，汽车是其中最重要的。故选C。二、单句填空1. (2018河北衡水中学) Theyre popular among many Chinese people as they provide an effective solution in places 44 its difficult to change from one kind of transport to another.【答案】where2. (2018河北石家庄市二中) Chinas industrial output is expected to rise by around 6.5 percent this year, marking the best performance since 2010, 42 the Made in China 2025 strategy (策略) helps to raise productivity and revenue(税收).【答案】as/because【解析】考查连词。句意：因为“中国制造2025”战略有助于提高生产率和收入，预计今年中国工业产出将增长6.5%左右，这是自2010以来的最佳表现。前后是因果关系，故填as/because。3. (2018河南南阳市一中) He kept pulling in the chain 50 the boat kept sinking.【答案】though/although/but【解析】考查连词。尽管船在下沉，但是他仍然不断地把金链子拉到船上。表示“尽管”，所以填though/although/but。4. (2018河南南阳市一中) These ancient roads had no particular name 42 the mid-nineteenth century;【答案】until【解析】考查连词。那些古老的路没有特殊的名字，直到十九世纪中期。表示“直到”，所以填until。5. (2018河南郑州市一中) 43 they got closer, they found it wasnt a rock but an opening in the ground.【答案】When / As【解析】本题考查了从句。句意为：当他们走近，才发现那是个地洞而不是岩石。此题是从句引导词判断题，联系文章，是时间状语从句。确定答案When / As。6. (2018重庆市一中) This is the name for special structures on buildings that are perfect at keeping structures together_49_the weather gets rough.【答案】when 【解析】考查状语从句。when引导时间状语“当时候”，故填when。7. (2018湖南郴州市一中) Tea drinking was widespread in China for about one thousand years 42 appearing in Europe.【答案】before【解析】考查状语从句。句意：饮茶在欧洲出现之前，它在中国已流传约一千年。故答案为before。8. (2018辽宁本溪高级中学) 44 he wasnt rich, he must have had some money to buy that armor.【答案】Though / Although / While【解析】考查状语从句。句意：尽管他不富裕，他必须要有钱买盔甲。根据句意可知这里用Though / Although / While。9. (2018宁夏银川市) The first thing she did 48 she got up every morning was to water the tulip.【答案】when/after10. (2018安徽六安市一中) But what 41 there is a fire where you live?【答案】if【解析】考查状语从句。句意：但是要是你住的地方着火了又怎么样呢？固定句式：what if（要是又怎么样呢），故填if.三、单句改错1. (2018石家庄市二中) I was in the kitchen with my wife and children while we heard a loud noise.【答案】whilewhen【解析】考查连词。句意：我与我的妻子和孩子们正在厨房里，这时候我们听到一声巨响。此处表示一个动作发生时突然出现了另外一个动作，而while表示两个动作同时进行，故将while改为when。2. (2018河北石家庄市二中) For another, to ensure efficiency in teaching and learning, the foreigners ability to speak Chinese matters much, so only with the help of Chinese can they municate with each other smoothly.【答案】sobecause/as【解析】考查连词。句意：另一方面，为了保证教与学的效率，外国人说汉语的能力非常重要，因为只有借助汉语，他们才能顺利地进行交流。后半部分是原因，故so-because/as。3. (2018河南南阳一中) The fans went wild though they thought his decision was a bit unfair.【答案】thoughbecause/as 4. (2018河南南阳一中) That I was in the second grade, my mother would frequently send me there to the little neighborhood store.【答案】ThatWhen【解析】考查状语从句。表示“当我上二年级的时候”，所以That-When。5. (2018河南郑州市) We were all busy working as all the work was done. Though we were tired out, we felt pleased on our way back home.【答案】asuntil/till【解析】考查状语从句。根据文章内容可知，我们一直工作，直到做完所有的工作。Until为“一直到”，as可译为“当.时候；因为”，故把as改为until/till。6. (2018哈尔滨师大附中) Therefore, we couldnt help collecting the rubbish after we left.【答案】afterwhen/before【解析】考查状语从句。因此，当我们离开时或我们离开以前，我们情不自禁地收集垃圾。结合句意，可知把after改成when/before。7. (2018湖北襄阳四中) I was about to give up while my father came to my assistance.【答案】while when【解析】考查固定句式。be about to do sth.when，正要做某事，这时候，故把while 改成 when。8. (2018湖南永州市) The day passed quickly after we knew it.【答案】afterbefore【解析】考查状语从句。句意：我们不知不觉地过了一天。可知应该把after-before。9. (2018湖南郴州市一中) Although it wont spoil the reading experience, but I do wish to have a perfect copy.【答案】but去掉【解析】Although和but前者是从属连词，后者是并列连词，不能在同一句中使用，故把but去掉。10. (2018内蒙古包钢一中) Whatever I look, I can see so many pretty flowers.【答案】WhateverWherever【解析】考查状语从句。句意：无论往哪里看，我都可以看到美丽的花。用副词，故WhateverWherever。四、单句翻译（并列连词）1. 改造城市需要花费很多的钱，但从长远来看还是省钱。【答案】The changes in the city will cost quite a lot,but they will save us money in the long run.2. 穿上你的大衣，不然你会着凉。【答案】Put on your overcoat,or you will catch cold.【解析】表示选择关系的并列连词。此类并列连词主or,or else,eitheror,otherwise，neithernor,notnor等。3. 这些建筑物已有50多年的寿命，因此不够坚固。【答案】These buildings were over 50 years old,so they were not strong enough./ These buildings were over 50 years old,therefore, they were not strong enough.【解析】so表示结果，意为“因此，所以，于是”。4. 我刚想走，突然电话铃响了。【答案】I was about to leave when the telephone rang.【解析】when并列连词，意为“就在那时”5. 树叶在落下，因为秋天已经到来了。【答案】The leaves of the trees are falling,for its already autumn.【解析】并列连词for引导的分句只能放在句尾，前面用逗号隔开，表示补充说明的微弱理由，只是为前面的内容提供判断的理由，有时译为并列的某种形式。这与because不同，because引导的是一种明确的因果关系，解释原因，常可回答why的提问。