on our way下载:英语问题

until
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。
since
ad.(常用于现在完成时或过去完成时)
1. 此后;从那时到现在
She left school three years ago and has worked as a nurse ever

since.
她三年前毕业,从那时起便一直当护士。
2. 之前,以前
prep.
1. (常用于现在完成时或过去完成时)自...以来,从...至今
I haven't heard from him since last year.
我自去年以来未曾收到过他的信。
conj.
1. (常用于现在完成时或过去完成时)自...以来,从...至今
It's been ten years since they married.
他们结婚到现在已经十年了。
She has been living a hard life since her husband died.
她自从丈夫死后,一直过着艰苦的生活。
2. 既然;因为,由于
He must have taken the book since it isn't here.
他一定是把书拿走了,因为书已不在这里了。
Since it is so hot, let's go swimming.
既然天气这么热,我们去游泳吧。

He won't be back UNTIL 5 o'clock.
I've been waiting here SINCE noon.

Until:有“最后”的意思。
Since:有“开始”的意思。

he will not be back until 5 o'clock

i have worked here since year 2000

until是到......为止的意思
since是自从的意思,一般用于现在完成时中.还有曾经的意思

until是到那时为止的意思
since是从那时开始的意思

since 还有鉴于的意思 表示显而易见的原因 语气较because弱 另外as也有因为的意思
Until 一般与not连用 构成not....until...结构 表示：直到...才