从方框中选择恰当的选项，补全对话。(有两项多余）

A: Mary, it's your bed time.    1  

B: Oh, Mum!   2    It's Friday evening and it's still early.

A: Yes. Tomorrow we have to get up early to catch the train to your grandpa's.

B:    4   OK, I'll go to bed right now.    3    Oh, Mum, do I have to brush my

teeth before I go to sleep?

A:    5    And don't forget to close the bedroom window.

B: I won't. Good night, Mum!

A: Good night!

Some people are worrying about the possibility ________ mobile phones could be responsible for a range of illnesses, from rashes(皮疹) to brain tumors．

A．that

B．why

C．how

D．whether