—Mary, are you sure your aunt ___ back from America?

—Yes. My mother ___ me. I am going to see her now.

A．has come; told

B．came; had told

C．had come; tells

D．is coming; has told

从分子的角度分析，下列解释错误的是（　　）

A．空气是混合物--空气由不同种分子构成

B．热胀冷缩--分子的大小随温度的改变而改变

C．湿衣服在阳光下容易晾干--温度升高，分子运动速率加快

D．电解水生成氢气和氧气--分子可以分成原子，原子再重新组合成新分子