Henry's job was to examine cars which crossed the frontier to make (21) that they were not smuggling (走私) anything into the country. Every evening, except at weekends , he (22) see a factory worker co 21. A. known B. clear C. obvious D. sure 22. A. would B. must C. might D. should 23. A. had B. ought C. used D. wanted 24. A. bicycle B. hill C. straw D. worker 25. A. when B. before C. while D. as 26. A. thinking B. suspecting C. expecting D. insisting 27. A. thoroughly B. through C. down D. up 28. A. carefully B. successfully C. obviously D. silently 29. A. return B. retreat C. retire D. rest 30. A. short while B. a period C. few minutes D. some time