GMP附录中将药品生产洁净室(区)的空气洁净度划分为
A.二个级别
B.三个级别
C.四个级别
D.五个级别
E.六个级别
参考答案:C
Everyone __________ here now. Let’s __________.
A.are; begin;
B.are; to begin
C.is; to start
D.is;start
大气层分几层()
A、4
B、5
C、6
D、7