A:波源是M, t=T/4
B:波源是M, t=3T/4
C:波源是N,t=T/4
D:波源是N, t=3T/4
把1.0 g含脉石(SiO2)的黄铁矿样品在氧气流中灼烧,反应完全后得0.78 g残渣,则此黄铁矿的纯度是( )
⑴Hello.____ A.Thank you.
⑵Here you are.____ B.Hi
⑶What's your name?____ C.OK.
⑷Good morning!____ D.Peter.
⑸Let's go.____ E.Good morning!