【练习答案】

　　一.1.A 2.B 3.A 4.A 5.B 6.C 7.A 8.D 9.B 10.D 11.A 12.D 13.D 14.A 15.C 16.C 17.A 18.D 19.C 20.C

　　二。 1. was built 2.was 3. to use 4. have become 5. are 6. be made 7. are getting 8. will be 9. are 10. be put

　　三。 1.riding 2.used 3.is 4.have not felt 5.is raining 6. is becoming 7.seeing 8.sayig 9.is grown 10.have been planted

　　四。 1.will fall 2.is allowed 3.have received 4.was showing 5.would not be 6.keep on 7.turn it off 8.be used for 9.pay for 10.Send for