—______ No pains, no gains.
A:No way.
B:Why not?
C:Not really.
D:Exactly.
纯种黄皱豌豆与纯种绿圆豌豆杂交,从理论上分析,F2中纯合体与新表现类型杂合体的数目之比为()
中共十一届三中全会后城市经济体制改革中心环节是( )