氦氖激光片的吸收光谱峰值为()
A.533nm
B.633run
C.733nm
D.833nm
E.933nm
参考答案:B
解析:氦氖激光片的吸收光谱峰值为633nm。
The dog ___________ like a fox. It has a pointed face ___________ a thick tail.[ ]
A. is, or
B. look, and
C. looks, or
D. looks, and
空接是指旅游团(者)抵达一站后,无导游人员迎接的现象。()