on + ing 形式和with （without)+ 分詞獨立主格結構
1)on + ing 形式：一般將介詞on + -ing形式理解為“分詞”（要有行為主體)而不是“動名詞”，意為 “當…時”，“一…就…”，相當于when 或as soon as，例如：
On hearing the news,she burst into tears.（一聽到這個消息，她一下子哭了起來。)
錯：On arriving in Beijing,it began to rain heavily.（一到北京，就開始下起大雨來了。)
由于句子的主語it并不是arriving的行為主體，該句語法不成立�？梢愿臑椋�
No sooner had we arrived in Beijing than it began to rain heavily.
2)with （without)+ 分詞獨立主格結構
She fell asleep with the lamp burning.（她開著燈誰著了。)
Almost every day the kids returned home with their hands and faces covered with mud and sweat.（孩子們幾乎每天回家時手上臉上都是泥和汗。)
當這樣的獨立主格結構中的動詞為 “be” 動詞時，往往省略，例如：
Every day the old teacher entered the classroom,with a poor bag under his arm.（每天，這位老教師夾著個破包走進教室。= with a poor bag being under his arm)
