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课件网) Unit 3 the world of science Using language 现在完成时 现在完成时表示过去的动作或存在的状态对现在造成的影响或结果，过去的这个动作或状态也有可能持续下去。 用法： 表示一个动作刚刚结束或完成，但这个动作所造成的状态或影响依然存在，即表示过去的动作对现在的影响或结果，强调现在的情况，常与副词just, already（多用于肯定句或疑问句）, yet（常用于疑问句或否定句句尾）连用。 表示从过去到现在曾经发生过或经历过某事，表达一种经验或经历，常与副词ever，never，once，twice，before等连用。 常与for或since连用。For 后面接一段时间；since后接时间点或表示过去时间的时间状语从句。 特殊句型 【This/That/It is the first/ second/ third… time that…】 【This/That/It is the+形容词最高级+名词+从句】 【It is/ has been…since...(过去式)】 This is the first time that I _____(watch) the play. This is the best film that I _____(see). It _____(be) six years since I came here. have watched have seen has been 现在完成时练习一 1、During the last three decades, the number of people participating in physical fitness programs _____(increase) sharply. 2、After several years of observation, the research group____ _____ (arrive) at the conclusion that language acquisition is faster when students are exposed to the situation where it is spoken. 3、Simon_____(attend) his father for such a long time that he understands almost every gesture of his father’s. 4、It is the first time that the local education authority _____ (make) such strict requirements on going-to-school time for primary and middle school students. 5、Over the last few years, the number of students participating in volunteer programs _____ (increase) sharply in our school. has increased has arrived has attended has made has increased 6、Researchers believe that since 2010 an average of nearly 35,000 elephants _____ (kill) annually on the continent. 7、With the help of high technology, more and more new substances _____ (discover) in the past years. 8、In the past few centuries，the lighthouses along North Carolina’s coast _____ (recognize) as signs of safety for travelers at sea. 9、I complained to the manager of the hotel about the poor service last week, but up to now，I _____ (receive) his reply. have been killed have been discovered have been recognized haven't received 10、Large quantities of water, as well as some other timely help including a medical team_____(offer) since the serious drought hit Yunnan Province. 11、More than one worker _____（send）to the training center to improve their working skills in the past three years. 12、Since 2011, the country _____(grow) more corn than rice. 13、 Regularly eating out seems to _____ (become) common for many young people in recent years. has been sent has grown have become have been offered 现在完成时练习二 将下面划线句子改为现在完成时被动语态。 Within the next 80 years, our lives may be changed beyond recognition by 3D printing. It has already affected many things in our lives, right down to the food we eat. For in ... ...
