Although the working mother is very busy……Although the working mother is very busy,she still devotes a lot of time to()her childen.A.look afterB.looking after选什么?为什么?

Although the working mother is very busy……
Although the working mother is very busy,she still devotes a lot of time to()her childen.
A.look after
B.looking after
选什么?为什么?

选 B,to在此为介词,后面只能跟名词或动名词