to 后可以加过去式吗 为什么我见到our time to saw

to 后可以加过去式吗 为什么我见到our time to saw Let us begin to have our class可以不加to吗?为什么 Often后加 have to 句型,要用过去式吗 owing to后可以加从句吗 为什么it is time后动词可以用过去式? to 后面可以直接加our么 be able to后为什么可以加doing? It's time for me to go to school 可以 不加to吗 our classmates want her to represent 为什么加to leave time to give our have gone to后可以加时间段的状语吗 be condemned to 后可以加动词原形吗?