—It____ be her. She left for Beijing yesterday.
A:needn't
B:can't
C:mustn't
D:may not
黄河下游水土流失严重,你认为与之有关的是( )
能卷舌(基因组成为AA)的父亲与不能卷舌(基因组成为aa)的母亲将基因传递给子代的过程如图.回答下列问题: