1.【2017·北京卷】If the new safety system _______ to use, the accident would never have happened.
A. had been put
D. would be put 【答案】A
【解析】句意：如果这个新的安全系统被投入使用过的话，这个事故就不会发生了。根据主句确定是对过去情况的虚拟，所以从句谓语用had done形式，此处根据句意可知是被动，用被动语态，故选A。
2.【2017·江苏卷】_______ not for the support of the teachers, the student could not overcome her difficulty.
A. It were
D. Was it 【答案】B
【解析】考查虚拟语气和倒装。虚拟语气中，be动词统一用were；虚拟语气的省略形式主要是把if省略，同时把were/should/had提前，即
were/should/had I…,故选B。句意：要不是老师们的支持，该生是无法克服她自己的困难的。
3.【2017·天津卷】My room is a mess, but I __________clean it before I go out tonight. I can do it in the morning.
A. daren’t
D. mustn’t 【答案】C
B. shouldn’t
C. needn’t
B. Were it
C. It was
B. were put
C. should be put
【解析】句意：我的房间很乱，但是在今晚我出去之前不需要打扫，我可以明天早晨再打扫。A.不敢；B.不应该；C.不需要；D.不许。根据句意，故选C。
4.【2017·天津卷】—Do you have Betty’s phone number? —Yes. Otherwise, I ______able to reach her yesterday. A. hadn’t been
D. wouldn’t be
B. wouldn’t have been
C. weren’t
【答案】B
【解析】句意：---你有贝蒂的电话号码吗？---有。否则我昨天就联系不到她了。根据标志词otherwise，相当于一个条件状语从句：If I hadn't have her phone number，即对过去的虚拟的条件状语从句，可以判断出主句用wouldn't have done表示对过去情况的虚拟，故选B。
5.【2016·北京卷】 I love the weekend, because I ________ get up early on Saturdays and Sundays.
A. needn’t B. mustn’t
D. shouldn’t 【答案】A
【解析】考查情态动词。句意：我喜欢周末，因为周六和周日我不需要早起。根据句意可知，周六，周日不用早起，故选A。
6.【2016·北京卷】Why didn’t you tell me about your trouble last week? If you ________ me, I could have helped.
A. told
D. would tell
B. had told
C. were to tell
C. wouldn’t
