1. I bought a watermelon yesterday.(一般疑问句) 2. They were young then. (否定句) 3. He did his homework last Saturday.(划线部分提问) 4. They visited lots of places.( 一般疑问句) 5. She went shopping the day before yesterday.( 划线部分提问) 6. He telephoned me again .(否定句) 7. I bought a watermelon yesterday.(tomorrow) 8. They were young then. (now) 9. He did his homework last Saturday. (at the moment) 10.He visited lots of places last year. (every year) 11.She went shopping the day before yesterday.(on Sundays) 13.The dog is eating a bone .(every day) 14.She washes the dishes every day.(改为一般疑问句) 15.Mary does the housework.(改为一般否定句) 16.He comes from China. (对划线部分提问) 17.I don’t go to work by car.(用He 做主语) 18.He usually watches TV at night.(用now, listen to the radio 改为现在 进行时) 19.They are typing the letters. (对划线部分提问) 20.He can read the letter. .(改为一般疑问句) 21. I can lift this table. (改为一般否定句) 22.Turn on the radio.(用He 做主语改为一般将来时)