we are going by train是什么时态
问题描述：
we are going by train是什么时态
是将来时为什么后面不加to
答
这是现在进行时表将来.
这里going是说明要走,但没说要到哪地方去,所以不加to.
如果后面有地点的话,要加to.
例:
He is going to Beijing by train.