感官动词有see,watch,observe,look at, hear, listen to ,notice有被动语态! 用法:感官动词+宾语+do,在用作被动语态要补出to. 例如:I heard her sing an English song just now. She was heard to sing an English song just now. 再问: 为什么有时加to 有时不加 再答: see sb do 表示看见某人做的全过程(我们习惯性省掉to do 当中的to) see sb doing 表示看见某人正在做的动作 当某人被看到在做某事的时候,要用 sb be seen to do ,也就是说to就还原 所以,在被动语态里用to