he was seen to go out by me为什么要用to go

网友回答

这是被动语态的句型,be -ed to do sth
======以下答案可供参考======
供参考答案1:
see let一类动词（具体什么动词忘了）肯定句时可以不加to，否定句时加。
供参考答案2:
he was seen to go out by me(被动)他出去被我看见了=l saw him go out(主动)我看见他出去了
供参考答案3:
see sb to do sth 看见某人做某事，强调结果
see sb doing sth 看见某人正在做某事，强调发生的动作正在进行