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
---What would you do if _________ eighty-year-old man fell down in front of you?
----I don’t know. Maybe I will help him.
A.a
B.an
C.the
D./
碘在()时,衰减曲线具有锐利的不连续性,其临界水平成为K缘。
A.11keV
B.22keV
C.33keV
D.44keV
E.55keV