A.顶交 B.回交 C.单交 D.复交
A.80% B.60% C.50% D.30%
A.Aa Aa B.AA AA C.AA aa D.Aa aa
A.延长B.缩短C.不变D.抽穗前延长，抽穗后缩短
A.50%－60% B.20%－30% C.70%-80% D.5%－10%
