is about to和is going to区别

问题描述:

is about to和is going to区别
主要是希望解释一下这题为何选A
Tom,together with his parents,_____the concert Saturday evening.
A.is going to
B.is about to
C.are about to
D.are going to

A和B的话主要区别还是在于A的意思更明确,B的话可以表示只是一种打算但是并不一定实施,而A就更明确了~
我记得大概是这样~
希望能够帮到您~