A:夏桀
B:商汤
C:商纣王
D:周幽王
让杂合体Aa连续自交三代,则第四代中杂合体所占比例为
A. It's a nice sweater.
B. It's on the line.
C. No, it isn't. It's on the chair.
D. Yes, I have. The coat is nice.
E. No, I haven't. I've got a new pencil.
下面各图形中,( )一定是轴对称图形.