固定桥修复的生理基础是（）
A.牙槽骨
B.牙槽嵴黏膜
C.基牙代偿力
D.牙周储备力及代偿功能
E.以上均不是
参考答案：D
外汇期货交易量较小的原因主要有（）。
A.欧元的出现
B.外汇市场比较完善和发达
C.外汇现货市场本身规模较小
D.投资者对外汇风险不敏感
I was not quite sure __________.
A．what is she looking for
B．why she came late for school
C．how did she deal with the problem
D．if she has arrived
