He has never been late for class, _____ he?[ ]
A. is
B. isn't
C. has
D. hasn't
答案:C
There is ____ “ m ” in the word “mother”.
A.a
B.an
C./
D.the
下列药物可采用的含量测定方法为
罗红霉素的含量测定()
A.汞量法
B.高效液相色谱法
C.溴量法
D.紫外分光光度法
E.抗生素微生物检查法