till和until一般情况下两者可以互换,但是在强调句型中多用until.并且要注意的是：如果主句中的谓语动词是瞬时动词时,必须用否定形式；如果主句中的谓语动词是延续性动词时,用肯定或否定形式都可以,但表达的意思不同.例如：
I didn't go to bed until（till） my father came back.直到我父亲回来我才上床睡觉.
It was not until the meeting was over that he began to teach me English.直到散会之后他才开始教我英语.
I worked until he came back.我工作到他回来为止.
I didn't work until he came back.他回来我这才开始工作.
Please wait until I arrived.在我到达之前请等我.