英语单项选择易错题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 workingC. 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
