气缸套分干缸套和（）。
A.水缸套
B.油缸套
C.湿缸套
参考答案：C
I wonder why Jenny to us recently. We should have heard from her by now. [ ]
A. hasn't written
B. doesn't write
C. won't write
D. hadn't written
哪项不是固定义齿的组成成分（）
A.固位体
B.基牙
C.桥体
D.连接体
E.以上都是固定义齿组成成分
