to 接going的目标,比如we are going to swim after lunch,目标是swim
这里的after lunch不是going的目标,而是描述什么时候going,因此不需要加to.
但是在一定的语境下加上to也不算错,只是很少这么说,因为很啰嗦,比如
when are you going to swim?we are going to after lunch,这时这么表达就没问题,只是啰嗦,而且这里的to是接的swim,而不是after lunch,swim只是被省略掉了而已!