A:C,H,O
B:C,H,O,N
C:C,H,O,N,P
D:C,H,O,N,P,S
银杏树与杏树相比,最主要的区别是( )
下列关于实验室制取氧气和收集,操作先后顺序中不正确的是 ( )
You had better _________ wine because you have to drive back home.