抖动绳子的一端,产生如图所示的横波,则绳上横波的波长为:( )
A.120cm
B.80cm
C.40cm
D.20cm
答案:C
— Has the little girl passed ______ P.E.test?
— She has tried twice, and the teacher will allow her to have _____ third try.
A.the; 不填
B.a; the
C.the; a
D.the; the
必须经省级药品监督管理部门批准后方可配制的是()
A.医疗机构制剂
B.第一类疫苗
C.二级野生药材物种人工制成品
D.没有实施批准文号管理的中药材