覆盖义齿短冠基牙牙冠的长度为龈缘上（）
A.3～8mm
B.3～6mm
C.3～5mm
D.3～4mm
E.齐龈或龈上3mm以内
参考答案：E
根据中文选择正确的句子。
1. 我有一条紫色的小船。[ ]
A. I have a pink doll.
B. I have a purple boat.
2. 请吃点鸡肉吧。[ ]
A. Have some chicken.
B. Can I have some chicken? Sure.
3. 吹气球。[ ]
A. Throw the plane.
B. Blow up the balloons.
4. 看，有多少个球？6个。[ ]
A. Look, how many balloons? Four.
B. Look, how many balls? Six.
5. 我们来吃生日蛋糕吧！[ ]
A. Let's eat the birthday cake.
B. Let's make a kite.
下颌角肥大口内截骨术的并发症（）.
A．面动静脉的损伤
B．面神经下颌缘支的损伤
C．颏神经损伤
D．腮腺区的肿胀和感染
