过去分词作表语
1.过去分词可放在连系动词be, get，feel,remain，seem，look,become等之后作表语，表示主语所处的状态
Tom was astonished to see a snake moving across the floor.汤姆很惊讶地看到一条蛇正爬过地板。
Finally the baby felt tired of playing with those toys.终于婴儿厌倦了玩那些玩具。

2．过去分词作表语时与被动语态的区别
过去分词作表语时，强调主语所处的状态;而动词的被动语态表示主语是动作的承受者，强调动作。
The library is now closed. (状态)图书馆现在关闭了。
The cup was broken by my little sister yesterday.(动作)昨天我妹妹把杯子打碎了。

3．感觉类及物动词的现在分词与过去分词作表语的区别
过去分词作表语多表示人自身的感受或事物自身的状态，常译作“感到……的”;现在分词多表示事物具有的特性，常译作“令人……的”。
We were amazed at what he said at the meeting.我们对他在会上讲的话很是惊讶。
His words were discouraging，which made many peoplediscouraged.
他的话令人泄气，使得很多人灰心丧气。