21. Astronauts_____ in their spaceship, but they frequently work outside now. A. were used to stay B. used to stay C. were staying D. had used to stay 22. People _____ that the earth is round before. A. were not used to believe B. used to believing C. would not use to believe D. did not use to believe 23. Tuberculosis_____ incurable before. A. use to be thought B. used to be thought C. used to think D. use to think 24. Formerly babies_____ of whooping cough. A. have died B. used to die C. would die D. both B and C 25. These city girls are used_____ in the field. A. to work B. used to lie C. would like D. to working 26. Newton_____ scientific books when a boy. A. used to read B. has read C. had read d. had been reading 27. I am sorry I am not_____ fast. A. used to drive B. used to driving C. use to drive D. use to driving 28. Frank used to work in a small shop. He_____ A. doesn't any more B. still does C. is now D. had never done anything else 29. Roy Trenton used to work in a small shop. He _____ in a small shop A. is working B. no longer worked C. no longer works D. doesn’t work 30. Roy Trenton used to drive a taxi. This means he_____ A. is driving it B. doesn’t drive it any more C. likes it D. didn’t like it