问题补充：
-----What were you up to when she dropped in?
------I for a while and some reading.
A. had played ; did
B. played; did
C. had played :was going to do
D. was playing; was going to do
答案：
A. had played ; did
B. played; did
(答案→)C. had played :was going to do
D. was playing; was going to do
解析：考查时态。由第一句可判断出第二句描述的事情发生在过去，for a while是相对于when she dropped in来说的when she dropped in，“我已经玩一会儿了”，因此该用过去完成时态．再看后一个动作，承接前面for a while，仍然在过去，had played for a while之后，因此应用过去将来时，表示过去那个时间将要发生的动作，故选C。
