从属连词till和until的意义相同，后者比前者的语气强些，但它们都表示“直到某时”。在till(until)引出的时间状语从句中，谓语动词的时态问题较为复杂；这给英语(精品课)学习者尤其是初学者带来了麻烦和困惑。本文就这种从句中的时态问题作一简述。
till(until)-从句通常表示时间的一点，而不表示时间的一段。同时,till(until)的用法具有正反两个方面的涵义：一是当从句的动作(状态)一开始，主句的动作(状态)就立即结束(消失)；二是主句的动作(状态)一直继续到从句的动作(状态)开始。因此，till(until)-从句的谓语动词往往用一般时态来表示。例如：
He does not go to school till(until) the cock crows at nine in the morning.
They will live in Chicago till(until) William finishes his thesis.
She waited till(until) I returned.
上面从句的一般时态用法是常见现象，是需要英语学习者掌握的。不过，在英语的实际运用中，till(until)-从句的谓语动词还可以用其他时态。
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。