从句与非谓语之间的转换 一、当从句的主语与主句的主语一致（定语从句的主语与先行词一致），如果从句中是： 1）从句用be动词作谓语 be + doing； 省略be；(例10) be + done；省略be；(例4) be + 介词短语；省略be；(例2) be + 形容词 / 副词； be变为being；(例9) be + 名词； be变为being；(例1) 2）如果从句中是其他行为动词作谓语 是一般现在时或一般过去时就一律用doing的进行时化简；(例3) 是完成时态或after引导的一般时态，用having done化简。(例7和11) 二、当状语从句的主语与主句的主语不一致时，也可按上面第一条中方法化简复合句。 化简后的短语前加上原从句中的主语即可（既是独立主格结构）。(例5、6、8) 1. When he was a young boy，he used to ask lots of questions. = Being a young boy, he used to ask lots of questions. 2. When he was in the classroom, he read his book aloud. = In the classroom, he read his book aloud. 3. They went to the teacher for help who taught them English. = They went to the teacher teaching them English for help. 4. When the earth is seen from space, it looks like a huge water ball. = Seen from space, the earth looks like a huge water ball. 5. When a guest comes to your room, you can say to him "Have a seat, please". = A guest coming to your room, you can say to him "Have a seat, please". 6. When his mother entered his room, he was playing the computer game. = His mother entering his room, he was playing the computer game. 7. After the two policemen entered the room, they turned off the light and waited there silently. = Having entered the room, the two policemen turned off the light and waited there silently. 8. Because there was no bus, I had to walk home. = There being no bus, I had to walk home. 9. Since it is fine today, we should have an outing this afternoon. = It being fine today, we should have an outing this afternoon. 10. While you are crossing the street, you should be careful. = While crossing the street, you should be careful. 11. When you have finished your homework, you may go home= Having finished your homework, you may go home. 化简：注意当时间状语从句或条件状语从句化简时可以将引导从句的连词带上，如(例10)。 1. When you are in doubt about the truth of this story, you may ask our head teacher. 2. Whenever you are in trouble, you can count on our support. 3. After the leaves on the trees turn dry, the trees have died. 4. Since you are to go to Beijing this afternoon, you should get everything ready before 12. 5. This is the famous professor, who is interested in computer design. 6. If he is not in the office, he must be out for lunch. 7. He is the naughty boy who was beaten by his father yesterday. 8. The old teacher, who works in that key school, is going abroad soon as a visiting scholar. 9. As soon as he got to Nanjing, he telephoned me. 10. He works so hard that he can enter Qinghua University. 11. If you come earlier tomorrow, I will help you with your English. 12. When he came back home, I was watching TV play. 13. The head-teacher, who followed a group of students, went into the office. 14. As soon as he heard the news, he jumped with joy. 15. The dictionary which contains a lot of examples and pictures in it has been published. 本文来源：https://www.wddqw.com/doc/074325935cbfc77da26925c52cc58bd630869353.html