Several weeks had gone by I knew the painting was missing.A. asB. sinceC. untilD. before

问题补充：

Several weeks had gone by I knew the painting was missing.

A. as

B. since

C. until

D. before

答案：

A. as

B. since

C. until

(答案→)D. before

解析：考查连接词的用法。A 因为， 当什么的时候 B 既然，因为 C 知道什么时候 D 在什么之前，…才， … 就，还没来的及。根据题意几周过去了，我才知道画不见了。所以选D 。