问题补充:
a post office, I stopped some stamps.
A. Passed, buying
B. Passing, to buy
C. Having passed, buy
D. Pass, to buy
答案:
A. Passed, buying
(答案→)B. Passing, to buy
C. Having passed, buy
D. Pass, to buy
解析:考查非谓语动词。第一空,主语I与pass之间是主谓关系,故用现在分词,在这作状语,第二空,stop to do 停下来去做另一件事,stop doing停止正在做的事,句意:通过邮局,我停下来买了一些邮票。所以选B。