2.现在分词的被动语态(being +过去分词)通常表示“正在被…”的意思。如强调现在分词表示的动作发生在谓语动词所表示的动作之前时，可用现在分词被动语态的完成式(having + been +过去分词)。
　　例如:
　　The bridge being built will be completed next month.正在修建的那座桥将于下月完成。
　　Having been kept out of the room about half an hour for his returning late，Tom was let in.汤姆回来晚了，所以被关在门外半小时左右才让他进去。
　　Now let’ s do some exercises:
　　1、用现在分词或过去分词结构改写下列句子:
　　Examples;
　　A student is reading a book over there. He is our monitor.
　　---The student reading a book over there is our monitor.
　　I saw him. He was running for the bus.
　　---I saw him running for the bus.
　　He sat there. He was watching the men at work
　　---He sat there watching the men at work.
　　Tom felt tired. He went to bed at once.
　　---Feeling tired, Tom went to bed at once.
　　I had worked for a long time, so I felt very tired.
　　---Having worked for a long time, I felt very tired.
　　The plan is about middle school education. It is being discussed.
　　---The plan being discussed is about middle school education.
　　1)The teacher is taking a walk on the playground. He is our teacher of English.
　　-----The teacher taking a walk on the play ground is our teacher of English.
　　2)The birds filled the air with music. They were singing in the trees.
　　-----The birds singing in the trees filled the air with music.
　　3) Here is a novel. It was written b Lu Xun.
　　-----Here is a novel written by Lu Xun.
　　4) The language is English. It is spoken in Australia.
　　-----The language spoken in Australia Is English.
　　5) Do you know the number of students? They are coming to the English Evening.
　　-----Do you know the number of students coming to the English Evening?
　　6) I could hear the boys. They were playing in the field.
　　-----I could hear the boys playing in the field.
　　7) He was glad to find the fire. It was burning brightly.
　　-----He was glad to find the fire burning brightly.
　　8) I watched them. They were dancing.
　　-----I watched them dancing.