为什么有时候要在is going to后面加be?

问题描述:

为什么有时候要在is going to后面加be?
为何句子:I’m going to be a basketball player like him.going to后面要加be?
又为何句子:She is going to take part in the high jump and the long jump 后面又不加be?

上面的be是实意动词,有成为的意思.下面的to后的take也是动词.