杆形卡环与圆环形卡环相比较，主要不足之处是
A．稳定作用差
B．支持作用差
C．固位作用差
D．弹性作用差
E．对基牙损伤大
参考答案：A
Since he started high school, he’s come to school by bike_____. [ ]
A. on his own
B. by his own
C. in his own
D. with his own
地下防水外防外贴临时性保护墙如铺两层卷材，其高度为（）。
A.30cm
B.45cm
C.50cm
D.60cm
