1. a big headache令人头痛的事情2. a fraction of 一部分3. a matter of concern 焦点4. a series of 一系列,一连串above all 首先,尤其是5. absent from不在,缺席6. abundant in富于7. account for 解释8. accuse sb. of sth.控告9. add to增加（add up to）10. after all 毕竟,究竟11. agree with同意12. ahead of time / schedule提前13. ahead of 在...之前（ahead oftime 提前）14. alien to与...相反15. all at once 突然,同时16. all but 几乎;除了...都17. all of a sudden 突然18. all over again 再一次,重新19. all over 遍及20. all right 令人满意的;可以

21. all the same 仍然,照样的22. all the time 一直,始终23. angry with sb. at/about sth.生气,愤怒24. anxious about/for忧虑,担心25. anything but 根本不26. apart from 除...外(有/无)27. appeal to 吸引，申诉，请求28. applicable to适用于29. apply to适用30. appropriate for/to适当,合适31. approximate to近似,接近32. apt at聪明,善于33. apt to易于34. around the clock夜以继日35. as a matter of fact 实际上36. as a result(of) 因此,由于37. as a rule 通常,照例38. as far as ...be concerned 就...而言39. as far as 远至,到...程度40. as follows 如下

41. as for 至于,关于42. as good as 和...几乎一样43. as if 好像,防腐44. as regards 关于,至于45. as to 至于,关于46. as usual 像平常一样,照例47. as well as 除...外(也),即...又48. as well 同样,也,还49. ashamed of羞愧,害臊50. aside from 除...外(还有)