英语选择答案及为什么8.Thatmusthavebeenalotofwork.yeah,itusthreedaystofinishit.A.takesB.hadtakenC.tookD.wastaking9.ScientistssaythatAmericans'lifeexpectancynearlydoubledoverthepastcentury.A.hadB.wasC.is

Question

英语选择 答案及为什么
8.That must have been a lot of work.
_yeah,it ____us three days to finish it.
A.takes B.had taken C.took D.was taking
9.Scientists say that Americans' life expectancy ___nearly doubled over the past century.
A.had B.wasC.is D;has
10.When MIke ___the front door,he coundn't find his key.So he had to wait for wife to come back
A.is to open B.was to open C.had opened D.opened

Answer 1

8.C.took 因为前句 是 对过去情况的肯定判断
9.D;has 因为 这是现在完成时 over the past century.是与现在完成时 连用的时间状语
10.B.was to open 当要开门时