用所给词的适当形式填空

1. We're doctors, so it's our _______ (duty) to save patients.

2. The road is _______ (crowd). Mr. Wang drives his car slowly.

3. What causes the _______ (ill)?

4. Did they enjoy _______ (they) in the party yesterday?

5. —Where is your mother, Beibei?

    —She is busy _______ (answer) the telephone.

10岁男孩，不慎跌下时，上肢外展，手掌先着地，跌伤后肘部肿痛，功能障碍。检查肘部明显畸形，肘关节固定于半伸位，肘后隆起，皮下青紫，压痛明显，最大可能诊断是（）。

A.尺骨鹰嘴骨折

B.伸直型肱骨髁上骨折

C.肘关节后脱位

D.肘部挫伤

E.肘关节前脱位