连接体熔模要求位于接近切端或牙合方1／2 ，其面积不应小于
A. 4mm²
B. 5mm²
C. 6mm²
D. 7mm²
E. 8mm²
连接体四周外形设计应
A. 圆钝，不能形成狭缝
B. 可形成V形结构
C. 邻间隙可不预留空间
D. 不必考虑强度、自洁性和美观性
51. Which of the following situations is most dangerous according to the passage?
Adults giving a lift to teenagers on the highway after 10 pm.
B. A teenager driving after midnight with passengers in the car.
C. Adults driving with three or more teenage passengers late at night.
D. A teenager getting a lift from a stranger on the highway at midnight.
52. According to Paragraph 3, which of the following statements is true?
A. Teenagers should spend more time learning to drive.
B. Driving is a skill too complicated for teenagers to learn.
C. Restrictions should be imposed on teenagers applying to take driving lessons.
D. The licensing authorities are partly responsible for teenagers' driving accidents.
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