15. Very few people understood this contract, _____was very obscure. 　　A. the language 　　B. the language of which 　　C. all it said 　　D. which it had said 　　16. Management often works hard to set up a situation _____work is done in series. 　　A. that 　　B. where 　　C. which 　　D. what 　　17. Although Tom is satisfied with his academic achievement, he wonders ____will happen to his family life. 　　A. it 　　B. that 　　C. what 　　D. this 　　18. We cannot leave this tough job to a person _____. 　　A. who nobody has confidence 　　B. in whom nobody has confidence 　　C. for whom nobody has confidence 　　D. who everyone has confidence of 　　19. Six out of every ten prisoners in chains are black, which is _____ the chain gangs call up images of slavery in centuries gone by. 　　A. where 　　B. when 　　C. what 　　D. why 　　20.Robots differ from automatic machines _____ after completion of one specific task, they can be reprogrammed by a computer to do another one. 　　A. so that 　　B. in which 　　C. given that 　　D. in that 　　21. His name will be crossed out from the list _____ he makes the same mistake again. 　　A. if 　　B. unless 　　C. because 　　D. though 　　22. Five minutes earlier, _____we may have caught the gunman. 　　A. and 　　B. but 　　C. or 　　D. so 　　23. _____ I'm supposed to work by myself, there are other people who I can interact with. 　　A. If only 　　B. So long as 　　C. Even if 　　D. As far as 　　24. We hope that all the measures against sandstorms, _____ was put forward by the committee, will be considered seriously at the meeting . 　　A. while 　　B. after 　　C. since 　　D. as 　　25. You are the best for the job _____ you apply your mind to it. 　　A. until 　　B. if only 　　C. in case 　　D. unless 　　26. Einstein claimed that matter and energy are interchangeable, _____ there is no 'absolute' time and space. 　　A. so that 　　B. even if 　　C. in case 　　D. in order 　　27. In a sense, men of this kind begin not so much with a musical theme _____ with a completed composition. 　　A. but 　　B. than 　　C. as 　　D. that 　　28. You must push away the many temptations that are always present _____ your schedule is useless. 　　A. and 　　B. but 　　C. or 　　D. for