用纯种的高秆(D)抗锈病(T)小麦与矮秆(d)易染锈病(t)小麦培育矮秆抗锈病小麦新品种的方法如下,下列有关此育种方法的叙述正确的是( ) 高秆抗锈病小麦 × F1 雄配子 幼苗 选出符合要求的品种 矮秆易染锈病小麦 A.该过程涉及基因重组及染色体变异 B.过程②为有丝分裂 C.过程③必须经过受精作用 D.过程④必须使用生长素处理---The dustbins ______ for three weeks.---In fact, they ______ once a week.A.haven't emptied; should have been emptiedB.haven't been emptied; should be emptiedC.haven't been emptied; should have emptiedD.haven't emptied; should have emptied