16. had sold
15. (who was) accused of killing
14. to distinguish between green and red/ to distinguish green from red
13. Next time you come in
12. is taking measures to prevent
11. (should) have nothing in common
20. seeing a second time
(19) 参考答案
19. no matter how difficult it is
18. (that/which are) made up of
17. can’t afford to equip every office with