据推测:原始大气中不可能存在的气体是[ ]
A.氧气
B.甲烷
C.氨气
D.氢气
A
--- There is something wrong with my radio.
--- ____. I can mend it for you.
A.It’s not good for you
B.You’re right
C.Never mind
D.That’s right
如图所示,在“用双缝干涉测光的波长”实验中,光具座上放置的光学元件依次为①光源、②________、③________、④________、⑤遮光筒、⑥光屏。对于某种单色光,为增加相邻亮纹(暗纹)间的距离,可采取________或________的方法。