15. All planes__________ before departure. A. will checked B. will has checked C. will be checked D. will been checked 16. Gold _______in California in the 19th century. A. was discovered B. has been discovered C. was discover D. they discovered 17. The woman ___________lives next door is a good doctor. A. who B. whom C. which D. whose 18. The table ____________legs are broken should be repaired. A. who B. whom C. which D. whose 19. Many people would be out of work if that factory _________down. A. closes B. closed C. had closed D. would close 20. If you___________ here yesterday, you_____________ me. A. were/would meet B. had been/ would meet C. were/ would have met D. had been/ would have met