题目内容
As it turned out to be a problem of no importance , we so much time looking into it .
| A．needn’t spend | B．didn’t have to spend |
| C．needn’t have spent | D．oughtn’t to spend |
C
解析试题分析：句意：因为结果证明这是个不重要的问题，我们本不必花这么多的时间调查它。从这句话的一般过去时态，可以判断AD是错的，B项是过去不必做，是表示事实，而这里表示的是虚拟语气，本不必做而做了，用needn’t have done，选C。
考点：考查情态动词的虚拟语气
–Can I get out at noon?
--No. Our school rules state that no student ____ be allowed out at noon, unless he has a request form.
| A．shall | B．will | C．must | D．can |
--I have to go now to pick up my daughter.
--If you ________ go, at least wait till the rain stops.
| A．can | B．may | C．should | D．must |
According to our school rules, students ________ not carry mobile phones when taking a exam.
| A．will | B．may | C．shall | D．need |
I have told you the truth. ________ I keep repeating it?
| A．Must | B．Can | C．May | D．Will |
— Is Jack on duty today?
— It ________ be him. It's his turn tomorrow.
| A．mustn't | B．won't | C．can't | D．needn't |
This cake is very sweet. You a lot of sugar in it.
| A．should put | B．could have put | C．might put | D．must have put |
It ________ have been her to leave her child alone and do whatever she wanted. She isn't such a person.
| A．couldn't | B．mustn't |
| C．mightn't | D．wouldn't |