问题补充:
His father told me that he for the United States three days .
A. has left; ago
B. had left; ago
C. left; ago
D. had left; before
答案:
A. has left; ago
B. had left; ago
C. left; ago
(答案→)D. had left; before
解析:考查时态。Three day ago三天前,与过去时连用;three days ago与过去完成时使用。可以:他的父亲告诉我在三天前他就去了美国。父亲告诉我已经用了过去时。去美国在他说之前,用过去完成时。故D正确。