listen to this 第三课中有个问题

Dentist: There we are. Now, open wide. Now, this won't hurt a bit. You won't feel a thing.

Patient: Aaaagh!

Dentist: Come along, now. Open your mouth. I can't give you the injection with your mouth closed, can I?

Patient: I ... I ... I don't want an injection. I hate needles.

Dentist: But it won't hurt you, I promise. None of us likes injections but sometimes they're necessary.

Patient: It will hurt, I know.

Dentist: Not at all. Look, I often deal with little children and they never complain; they're always very brave. Now, open wide.

Patient: I don't want an injection.

Dentist: But how else can I take out your tooth? It would hurt even more without an injection, wouldn't it? And the reason we're taking it out is because it's hurting you, isn't it? Once you've had an injection and I've taken out the tooth you won't have any more