下列药物添加剂适用于抑制细菌感染的是()。
A、黄霉素
B、喹乙醇
C、金霉素
D、阿美拉霉素
参考答案:C
(2013·东北四市一模)After visiting Harbin, most of the foreign friends said they would never forget the time ________ they had spent.
A.that
B.what
C.when
D.at which
.测量中的读数误差,属于()。