经常储备定额是______。
A．物资平均日耗量×合理储备天数
B．物资价值×储备天数
C．物资储备成本×储备时间
D．物资占用空间×储备天数
参考答案：A
—I just found an MP4 on my desk. Whose MP4 is this?
—Oh, that ______ be John's. He's been looking for his MP4 for an hour. [ ]
A. must
B. might
C. can't
对关节的描述，正确的是（）
A.关节面表面有一层纤维软骨覆盖
B.所有关节均有关节盘
C.关节囊的纤维膜与滑膜之间腔隙称为关节腔
D.关节腔内为负压，并有少量滑液
E.所有关节均有囊内韧带
