50. It is / has been +一段时间+since从句(从句中如为延续性动词,则实际表示的意思相反)

It is two years since he drank.他不喝酒已两年了.

[各个击破]

49. more……..than与其…….不如……..

He is more nervous than frightened.　　

48. What if……..要是…….怎么办？

What if he doesn’t come tomorrow?

47. not / neve等表示否定的词与比较级连用表示最高级，如：

-----Do you agree with his suggestion? -------I can’t agree more.

46. can not ( never) ……too +adj. (adv. ) / adj. (adv.) + enough “越……越好”“非常”

　 too + adj. ( anxious / eager / willing / ready / glad等)+to do….表示肯定意思

I can’t thank you enough.我非常感激你.

He was too glad to see his father.=He was very glad to see his father.

45.While置于句首可表示As long as 或 Although

While there is life there is hope.

While I admit his good points, I can see his bad ones.

42. By the time +从句(一般现在时/过去时)，主句(将来完成时/过去完成时)

43………., as is often the case with sb. / as is usual with sb.(as引导非限制性定语从句)

44 in case / lest / for fear that…….(从句中用陈述语气或should do)

41. I like / hate / appreciate it that / when等从句 (it表示后面从句的这种情况)

I appreciate it if you will give me a hand.

40. It’s important / necessary / strange / surprising….+that……(用陈述语气或should do)

39. I’d rather (not) do / have done……我宁愿…..

　I’d rather +从句(从句中用过去时或过去完成时)