A:①②③
B:②③④
C:①③④
D:①②④
用基因型为AaBbCc(无连锁)水稻植株的花药培养出来的单倍体植株,经染色体加倍,可培育出多少种纯合子植株( )
在平面直角坐标系中,△ABC的三个顶点坐标分别为A(2,-4),B(3,-2),C(6,-3).
Fire can____ down a lot of trees. It can____ people, too. We must be____with fire. We mustn't____ in the forest. We mustn't play____ fires at home. We mustn't play with matches either.