45.You  can use my car ………………..you drive carefully. A.unless B. as long as C. as soon as D. when 46. If everyone……………….an extra hour a day, it would greatly increase production. A. work B. works C. working D. worked 47. If energy…………………….inexpensive and unlimited, many things in the world would be different. A.is B. were C. will be D. would be 48. Don't bother to ring me ………………….it's important. A.unless B. in case C. if D. as 49.If you help me with this exercise, I …………….do the same for you one day. A. will B. would C. was D. am 50. According to the timetable, if the train…………..on time, we………….arrive at 5.30. A. leaves/ would B. left/ would C. leaves/ will D. was leaving/ would 51. If I could speak Spanish, I …………………..next year studying in Mexico. A. will spend B. had spent C. would spend D. would have spent 52. The bus won't stop ………………….you ring the bell. A. if B. as soon as C.  providing D. unless 53. You'd  better  take a coat ………………..it gets cold. A. if B. in case C. as long as D. while 54. If you ………………..to my advice in the first place, you wouldn't be in this mess right now. A. listen B. will listen C. listened D. had listened 55. If it …………….fine tomorrow, we will go to the coast. A. will be B. was C. is D. being 56. You …………..yourself ill if you don't eat properly. A. were to make B. make C. would make D. will make