39. ask for 要求
40. attach importance to 重视
41. pay attention to重视catch one's attention引起…注意/重视
42. available可得/买到的
There is no ticket available.
43.average平均on(the) ~
44. be aware of = realize意识到be sure一定要，肯定
He apologized to us for the mistake as soon as he was aware of it.
Be sure not to be late for the meeting.
I'm sure the play will be a great success.
45. back up支持
46. background背景
