until和till的时态

　　1.由于till(until)-从句往往具有开始或结束的体貌涵义,其谓语动词可以用完成时态来强调这种体貌。

　　例如：

　　Don't get off the bus till(until) it has stopped.

　　He spoke no word and made no sight till(until) I had finished the tale.

　　2.till(until)-从句的谓语动词可以用进行时态。

　　一方面表示动作的持续性,形象生动；另一方面表示情况的演变和新的发展,把从句所表示的事情与主句所表示的动作(状态)联系在一起。

　　例如：

　　He can't tell which way she is swinging till(until) she is coming around.

　　I never saw this drop till(until) I was flying headlong through the air.

　　3.英国语言学家伦道夫夸克教授等人在1972年出版的专著《当代英语语法》(A Grammar of Contemporary English)中认为：till(until)-从句的谓语动词不能与助动词shall或will连用。而中国语言学家周海中教授在1987年发表的论文《关于英语中till及until的用法问题》中却指出：当助动词shall和will用于till(until)-从句时，它们不是表示将来时间，而是表示情态意义。他用实例说明这种用法：

　　I won't leave you till you shall be well taken care of. (C. Dickens: Little Dorrit)

　　Those are as fixed as fate; and my voyage is only now delayed until the weather shall permit my embarkation. (M. Shelley: Frankenstein)

　　Then the lovely pale-lilac irises will come out in all their showering abundance of tender, proud, spiky bloom, till the air wi11 gleam with mauve, and a new crystalline lightness will be everywhere. (D. Lawrence: Phoenix)

　　They're commandeering power, water, land, and strategic materials till hell won't have it. (H. Wouk: War and Remembrance)

　　周海中教授在论文中还指出：should和would也可以用于till(until)-从句，同样表示情态意义。例如：

　　Carol waited till Kennicott should rescue her. (S. Lewis: Main Street)

　　Therefore she moved along the bank till he would look up. (D. Lawrence: Women in Love)

　　由上可见，till(until)-从句的谓语动词用何种时态，应视内容和语气而定。