543.Did Alan enjoy seeing his old friends yesterday?
Yes,he did.He ______ his old friends for a long time.
A.didn't see
B.wouldn't see
C.hasn't see
D.hadn't see
544.Danny _______ hard for long to realize his dream and now he is popular.
A.works
B.is working
C.has worked
D.worked
543.答案是D;for a long time常与完成时连用；此题中see动作发生在enjoy之前，故应用过去完成时。
544.答案是C;此题强调work hard对现在的影响，故应用现在完成时。
