分类：教育/科学-外语学习
问题：2.五道英语选择题，请详细说出原因。。。4.Youlooksot 
4.You look so tir.You___have stayed up late again.a.should b.can c.may d.must5.Some people who don,t like to talk much are not necessarily shy;they___just be quiet people.a.must b.may c.should d.would6.But for their help,we____the program in time.a.can not finish b.w4.You look so tir.You___have stayed up late again.a.should b.can c.may d.must5.Some people who don,t like to talk much are not necessarily shy;they___just be quiet people.a.must b.may c.should d.would6.But for their help,we____the program in time.a.can not finish b.will not finish c.had not finished d.could not have finished7.Don't you think it essential that every resident of Nanjing____spare no effort to make contributions to Nanjing 2014 Youth Olympic Games?a.should b.will c.shall d.would8.He chose to teach in a western province,though he___in the city for a better life.a.could stay b.should be c.must have stayed d.had stayed
回答：4.选D，must have done sth...肯定做了。。。（十分有把握）       may have done sth...有可能做了。。。（可能性较大）       might have done sth...有可能做了。。。（可能性较小）       should have done sth...本应该做。。。（实际上没做）       can have done sth...本来能够做。。。5.选B. must be 肯定是。。。       may be 有可能是。。。       should be 应该是。。。       would be 会是。。。6.选D. But for引导的从句，其主句部分要用虚拟语气。本题考察的是与过去相反的虚拟语气，but for=if...had not been for...,即：If  had not been for their help, we couldn't have finished the program in time.7.选A。essential引导从句，从句要用虚拟式，同necessary一样。例：it is essential/necessary that (should) do sth.8.选A. could stay 能够呆在。。。       should be 应该在。。。       must have stayed...肯定在。。。呆过       had stayed 过去在。。。呆过