题目内容：

have you found a way to solve the problem?
no ,I ______it carefully,but I havent come up with one yet.
A am cnsidering B considered C have been considering D had considered
为什么不选A C D

优质解答

后半句是现在完成时,表示过去发生且持续到现在的动作（或与现在有关联的动作）,那么前半句时态也必须是表示过去的.用排除法,A是现在进行时,表现在,不对；C是现在完成进行时,强调现在持续进行,不对；D是过去完成时,表...