顶交法
参考答案:选育一个遗传基础广泛的品种群体作为测验中,来测定自交系的配合力。
The two brothers carried a ______ bed into the room.
A.double
B.deal
C.slight
D.opposite
_____ of the students in our class _____ girls.
A.Three fives; is
B.Three fifths; is
C.Three fifth; are
D.Three fifths; are