1．My room is a mess，but I __________not clean it before I go out tonight.I can do it in the morning.
解析：考查情态动词。句意：我的房间很乱，但是在今晚我出去之前不需要打扫，我可以每天早晨打扫。故填need。
答案：need
2．Why didn't you tell me about your trouble last week？If you ________(tell)me，I could have helped.
解析：句意：上个星期你为什么不告诉我你的麻烦事？如果你告诉我了，我就能帮你。根据句意和相关信息判断，条件句表示与过去事实相反的假设，此时从句用过去完成时，主句谓语用“情态动词＋have done”形式。
答案：had told
