“How long do you suppose it is he left for Japan?” “No more than half a month.”A. whenB.

问题补充：

“How long do you suppose it is he left for Japan?” “No more than half a month.”

A. when

B. before

C. after

D. since

答案：

A. when

B. before

C. after

(答案→)D. since

解析：考查连词。When 当什么时候，before 在什么之前，after 在什么之后，since 自从，句意：你认为自从他动身去日本多久了？仅仅半个月。所以选D。