外科手术后伤口感染常发生在术后()。
A.8~12小时
B.1~2天
C.3~5天
D.7~8天
E.9~10天
参考答案:C
—Where is your uncle?
—He ______ to Hong Kong. He will come back in two weeks. [ ]
A. has been
B. had been
C. has gone
D. went
表示零件表面经过机械加工后凹凸不平程度的是()。
A、配合系数
B、精确度
C、亮度
D、粗糙度