A:C3H6与C5H10
B:C4H6与C5H8
C:C3H8与C5H12
D:C2H2与C6H6
一 We have five kinds of schoolbags. Do you like this one?
一 No. Can you show me ?
在生物学上,“大鱼吃小鱼,小鱼吃虾米”描述的是( )