4道高中英语选择题答案已给出 只求解析1 In --- prepration for the landing of ch

4道高中英语选择题
答案已给出 只求解析
1 In ___ prepration for the landing of chang e's 1 scientists need
___ knowledge of whether changes
A the the B a \ C \ a D the a (C)
如果填和这个类似的空有什么规则么?
2 It is the first time he has come here and now it is high time that he ____
A should be shown B was shown (B)
(it is high time 是什么意思呢? 有什么用法)
3 Your telephone number again ? I ____ quite catch it
---It is 9568442
A didn't B couldn't C don't D can't(A)
(为什么不能选D呢? )
4 As ___ We returned the questionaire ahead of time
A instructed B instructing C to instruct D instruct(A)
(不懂..)