一般表示被動,表示動作已完成的,用過去分詞.如：
Seen from the top of the hill,the village is too small.
表示主動或者表示動作動作正在進(jìn)行的,用現(xiàn)在分詞.但是如果要強(qiáng)調(diào)非謂語動詞的動作先于謂語動詞發(fā)生時,可以用現(xiàn)在分詞完成式.如：
Coming into the room, he found his father angry.
Having been hit by the big boy on the nose, the little boy began to cry.
如果用作目的狀語或者表示將來的動作就用不定式,但是only+ to do特殊,是作結(jié)果狀語.如：
I come here only to say good-bye to you.　目的狀語
He searched the room only to find nothing. 結(jié)果狀語

獨(dú)立主格表示的是所填非謂語動詞和句子主語沒有任何關(guān)系（主謂關(guān)系或者動賓關(guān)系）,那么久在這個非謂語動詞前面加上自己的邏輯主語,這就叫獨(dú)立主格.如：
The test finished, we began our holiday.
Weather permitting, we are going to visit you tomorrow.