Text 1

　　21. D a cause of undesirable behaviors

　　22. B learn from advertisers‘experience

　　23. A adequately probe social and biological factors

　　24. C occurs without our realizing it

　　25. Dquestionable

　　Text 2

　　26. C dishonoring.

　　27. A obtain protection from Vermont regulators.

　　28. A managerial practices.

　　29. B the mature of states‘ patchwork regulations.

　　30. B the authority of the NRC will be defied.

　　Text 3

　　31. A uncertainty and complexity.

　　32. A strict inspection.

　　33. B has been examined by the scientific community.

　　34. D scientific work calls for a critical mind.

　　35. D Challenge to Credibility at the Gate to Science.

　　Text 4

　　36. C unions have enlarged their public-sector membership.

　　37. D Public-sector unions seldom get in trouble for their actions.

　　38. B indirectly augmented.

　　39. C may be a barrier to public-sector reforms.

　　40. A disapproval.