选择合适的连词完成句子。

1．He doesn't know ________ to get there．I think he can take a bus．

2．He doesn't know ________ to buy a good camera．I think he can get one in ABC Mall．

3．He doesn't know ________ to hand in the homework．I think he may do it tomorrow．

4．He doesn't know ________ to ask for help．I think he can go to the teacher．

5．He doesn't know ________ to buy so much food．I told him there's nothing in the fridge．