1. They ______ on the program for almost one week before I joined them, and now we _____on it as no good results have come out so far.

A. had been working; are still working    B. had worked; were still working

C. have been working; have worked      D. have worked; are still working

此题的时间参照点是before I joined them,，所以第一个空应该用过去完成进行时，第二个空根据时间now用现在进行时。

2. It would be a good idea to use a plastic bottle, ___cut off, as a container to grow young plants in.

A. of which the top      B. the top is       C. the top of which       D. with its top

此题是独立主格结构，如果题干改为 ____is cut off,答案则为A或C

3. ______ is it _____ has made Peter _____ he is today?

A. What; that; that  B. That; that; what  C. What; what; that  D. What; that; what

用还原法则为 It is what that has made Peter what he is today k可知是强调句式。

4. Before he went abroad，he spent as much time as he _____ English.

A. could learning   B. learned  C. to learn   D. could learn

spend time (in) doing sth 如果改为he did what he ______, 则答案为could to learn.