如图所示，A为电磁铁，C为胶木秤盘，A和C(包括支架)的总质量为M，B为铁片，质量为m，当电磁铁通电时，在铁片被吸引上升的过程中，轻绳上拉力F的大小为(　　)

看图，读一读，将字母序号写在横线上。

A. I like this plant. It's short. It has small leaves. It has three red flowers.

B. This is my plant. It's small. It has two small leaves. I water it every day.

C. There are two seeds. They are under the ground. They drink the rain water.

D. I have a new plant. It's green. It has long leaves. It has small flowers too.

下面全部能用儿化音读的一组是（    ）。