21. according to－根据
22. specialize in doing sth－擅长做某事
23. serve as－作为
24. at one time－在同一时间
25. tend to－倾向于
26. interest in－兴趣
27. due to－由于
28. lead to－导致
29. at least－至少
30. contrary to－相反的
31. be equal to－等于
32. contribute to doing sth－有助于做某事
33. live in－生活在
34. be dedicated to doing－致力于做
35. deal with－处理
36. belong to－属于
37. it is estimated that－据估计，
38. be resistant to－抗
39. result from－结果
40. consist of－包括
