Question

明天考英语，两道题，急！！！

In such a fierce competition, a person has to make every effort if he ______.
A. has succeeded B. is to succeed C. would succeed D. will succeed

You look very tired. You ____ late last night.
A. needn’t sit up B. didn’t need to sit up C. shouldn’t sit up D. needn’t have sat up
要解释，谢谢！！！

Answer 1

1. B 意思大致是在如此激烈竞争的比赛中，如果想要成功必须全力以赴。A是完成时态不表将来，C是will的过去would，BD均表将来，但Be to do表示“想，打算”，相当于intend, want。will do sth是一般将来时，代表将要做某事情，
2. C 意思是你看起来很累，你昨晚不应该熬夜的。should not do 是表建议，你不应该做某事；而need have done应该是表示本应该做某事却没有做，他的否定形式needn't have done 就是表示本没有必要做某事而做了。例如：You needn't have stayed.意思就是 你本没有必要留下来（实际却留下来了）。其实刚开始，我第一感觉也是选D，但后来想了想，貌似结合前面那句话，C更贴切哦。纯属个人观点哈。

Answer 2

In such a fierce competition, a person has to make every effort if he ______.
A. has succeeded B. is to succeed C. would succeed D. will succeed
答案为B if he is to succeed的意思是“如果他一定要成功”，这是一种常用结构，全句“在这样激烈的竞争中，一个人如果一定要成功，就得全力以赴”。再如You must water the flowers if they are to survive.这些花如果一定要活下来，你就得给它们浇水。

You look very tired. You ____ late last night.
A. needn’t sit up B. didn’t need to sit up C. shouldn’t sit up D. needn’t have sat up
答案为D,但最好应是“shouldn't have sat up本不该熬夜的”，选D则为“你看上去很累，昨晚你本不必熬夜的”，本题考查情态动词的完成式，表示对过去某一行为的某种语气。

追问

be to 不是和should的意思一样的吗？老师说的。

追答

老师说得很好，是相似的，此题用should也对。should更多的侧重于“竟然，万一”之意，如You'd better take an umbrella if it should rain.你最好带把伞，以防天万一下雨。
如果你不明白可以再追问我。

Answer 3

1，B,条件状语从句从句不能用将来时，这里B一般现在时表将来
2，D虚拟语气，情态动词加完成时，needn't have done,你昨天本不必熬夜的

Answer 4

B
C