it is time for sth
it is time (for sb 常常省略) to do sth.
通常说 it is time for class.就可以了。
不说it is time to class.因为class 作动词用时的意思是:
把...分类(或分等级)
it is time for class ,class为名词。
it is time to class,class为动词。
不可以,这里只能用for
可以互换
to 这里表示动作的方向
事实上也可以说成it is time to go to class
同意lidake2005,或者说it's time to go to class