题目：
选择正确的引导词补全句子
1.I don't know ________ he will come.(that,if)
2.I believe ________ he is a good teacher.(that,if)
3.I want to know ________ you join this club.(why,what)
4.They asked ________ I came from.(if,where)
5.I can't remember ________ I bought this bag.(when,that)
答案：
1.if 2.that 3.why 4.where 5.when
