Ⅰ.选择括号中的词汇填空
【小题1】Have you done your homework_______?(for, just, yet)
【小题2】I have _______been to Chengdu.(for, never, yet)
【小题3】He has worked there ________he left school.(already, just, since)
【小题4】She has known Sam________nine years.(since, for, yet)
【小题5】Have you ______ridden a horse?(ever, for, yet)
【小题6】He has_______finished his homework.(ever, just, yet)