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Over+时间短语 时态用法总结WORD CHOICE: since, for, during, overUse since to say that something started at a point in time in the past, and is still continuing : He has been living in Leeds since 1998. | Weve known about it since May. Since is usually followed by a time expression (last year, this morning, 4 oclock etc) or by the simple past tense. Use the present perfect or the past perfect in the other clause : I have loved movies since I first went to the cinema. |He had been seriously ill since Christmas.! Speakers of British English usually say it is a long time/two weeks etc since ., and speakers of American English it has been a long time/two weeks etc since ., but both uses are correct : Its weeks (BrE)/Its been weeks (AmE) since I saw Grandma.Use for when you state the length of time that something has been happening : We have known each other for ten years (NOT since ten years). | I had been waiting for hours (NOT since hours). |I havent seen him for ages (NOT since ages).During and over are used when you state the period of time in which something happens or changes : During her first year at college, she had several boyfriends. | Over the last six months, crime has doubled.“over the past/last +时间短语“修饰句子谓语，表示during/through用现在完成时 新prep-188. Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.新PREP-224. (GWD-12-Q13) Although energy prices have tripled in the United States over the last two years, research indicates that few people have significantly reduced the amount of driving they do or made fuel efficiency a priority when shopping for cars.旧PREP138 According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, the surface temperature in Alaska, Siberia, and northwestern Canada has increased over the last thirty years by about five degrees.大全409 In the last ten years, the dropout rate among Black high school students has fallen substantially, while the number of Blacks attending college has more than doubled大全986 Turkeys economy has grown prodigiously over the past ten years, with an average annual increase of about eight percentone of the highest growth rates in the world.特例：新prep-220. (GWD-24-8) The results of the companys cost-cutting measures are evident in its profits, which have increased five percent during the first three months of this year after falling over the last two years. 新PREP-257. (GWD6-Q30) Though subject to the same wild-animal control efforts that killed off almost all the wolves in North America over the past century, the coyote, because of its amazing ability to adapt to the presence of humans, has been able to expand its range into Alaska and Central America.大全142 As U.S. nuclear attack submarines prowl their familiar haunts deep within the oceans of the world these days, they increasingly are engaged in missions far different from the tasks for which they were built and for which their crews were trained over the last forty years.“over the past/last +时间短语“修饰句子宾语，不影响动词的时态 旧PREP2-119.After determining the levels of calcium carbonate and the types of fossilized algae present in core samples taken from the bottom of Lake Titicaca in the Andes, a group of scientists was able to reconstruct the history （of precipitation in tropical South America） over the past 25,000 years. 这个句子，over the past 25,000 years修饰的是the history，自然与reconstruct这个动作无关了。大全775 The main reasons for the phenomenal growth （of agribusiness over the last fifteen years） are elevated land prices, retail marketing networks based on produce imported from other states, and decreased competition from developers. 这个也一样，over the last fifteen years 修饰的是growth，不影响后面的动词形态。Over the next+时间短语 要用将来时，will/could/would大全726 The delinquency rates on mortgages for office buildings, hotels, shopping malls, and other commercial properties held by the nations insurance companies have increased sharply in recent months, leading to predictions that foreclosures on these types of loans could double over the next three years大全023 Tiny quantities of more than thirty rare gases, most of them industrial by-products, threaten to warm the Earths atmosphere even more rapidly over the next fifty years than carbon dioxide will大全976 Seeking to spur science education, the National Science Foundation will spend $25 million over the next ten years to promote science in elementary and secondary schools大全976 Seeking to spur science education, the National Science Foundation will spend $25 million over the next ten years to promote science in elementary and secondary schools大全726 The delinquency rates on mortgages for office buildings, hotels, shopping malls, and other commercial properties held by the nations insurance companies have increased sharply in recent months, leading to predictions that foreclosures on these types of loans could double over the next three years大全886 Tiny quantities of more than thirty rare gases, most of them industrial by-products, threaten to warm the Earths atmosphere even more rapidly over the next fifty years than carbon dioxide will旧PREP1164 One automobile manufacturer has announced plans to increase the average fuel efficiency of its sport utility vehicles by 25 percent over the next five years, an increase that would amount to roughly five miles per gallon and would represent the first significant change in the fuel efficiency of any class of passenger vehicle in almost two decades.Over +时间短语 过去时新PREP-210. (GWD-12-Q31) Emily Dickinsons letters to Susan Huntington Dickinson, which were written over a period beginning a few years before Susans marriage to Emilys brother and ending shortly before Emilys death in 1886, outnumber her letters to anyone else.旧PREP1167 It is possible that, like the Volkswagen, whose unchanging exterior over decades concealed many changes in its internal machinery, many prehistoric microbes evolved without significant modification of their sheaths.新prep-208. (GWD-11-40) Scientists who studied the famous gold field known as Serra Pelada concluded that the rich lode was produced not by the accepted methods of ore formation but by swarms of microbes that over millions of years concentrated the gold from jungle soils and rivers and rocks.（that从句修饰microbes，over修饰concentrated）（特例）旧PREP2-72.Several educational research groups are denouncing the mayors proposal of a system by which individual teachers would be given raises or bonuses if test scores show that their students mastery of reading skills has improved over a nine-month period.（表during）大全571 Archaeologists have discovered that, （over five thousand years ）ago, Mesopotamian cooks were preparing chicken with coriander and tamarind, just as Egyptian cooks are still doing today. 这个句子里,over 是和 five thousand years一体的,over five thousand years ago,是说5000多年以前,而不是说持续了5000年.over不表示during
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