理想的引导骨再生膜应具备的特性不包括（）
A.可吸收
B.屏障作用
C.不可容忍切口裂开
D.价格便宜
E.易于使用
参考答案：C
I'm hungry. I want _______. [ ]
A. something eating
B. something to eat
C. eat something
D. to eating something
—Which is______，the sun，the moon or the earth?
—Of course，the moon is.
A．biggest
B．the biggest
C．smallest
D．the smallest
