Grammar exercise: Choose the best answer to complete the sentence.1.The reading room________ yesterday afternoon.A.cleaned B.is cleaned C. was cleaned2.The workers were ________ to work ten hours a day.A.makeB.madeC.making3.Food________in a cool place in summer.A.must keep B.mustn’t keep C.must be kept4. Coal can ________ to produce electricity for agriculture and industry.A. have used B. used C. be used5. The room isn’t dirty any more .it__________.A.be cleaned B. cleaned C. has been cleaned6. The bridge ___________ next year.A. completed B. will be completed C. being completed7. Your new computer will soon become outdated, because technology_______so fast.A. is being developed B. developed C. has developed8. This place has________.A. been destroyed B. destroyed C. destroy9. All the preparations for the task ________ , and we are ready to start.A. completed B. complete C. have been completed10. The construction of the laboratory ____by the end of next month.A. must be completed. B. must completed. D.will be completing