When you apply for a job, you must present your credentials. 当你申请工作时，你必须递交你的有关证件。（同时）
When the students heard the teacher’s footsteps, they all atopped talking. 当学生们听到老师的脚步声时，他们都停止了讲话。（从句动作发生在前）
be about to do … when … 正要去做某事，突然……
be doing … when … 正在做某事，突然……
be on the point of doing … when … 正在做某事，突然……
We were about to start when it began to rain. 我们正要动身，突然天下起雨来。
The game had hardly/scarcely/barely begun when it started raining. 比赛刚刚开始就下起雨来。
When the teacher paraphrased the text in English, the students listened attentively and took notes. 当老师用英语解释课文时，学生们聚精会神地听并做着笔记。
I can learn while I work. 我可以边工作边学习。
We were having breakfast as she was combing her hair. 她梳头时我们在吃早饭。
It will warm up a little bit on Sunday as the cold front passes. 寒流一过，星期日就会有点暖意了。
1.（2016·全国新课标卷III·语法填空）Over time, 45 the population grew, people began cutting food into small pieces so it would cook more quickly.
2.（2016·四川卷·语法填空）The mother held the baby in her front paws much the way a human does. 46 it cried, she rocked it back and forth and gave it little comforting pats.
I have finished my dissertation before my supervisor went abroad. 在我的导师出国之前，我已完成了我的学位论文。
I’ll be back before you have left. 你离开之前我就会回来。
It may be many years before we meet again. 可能要过许多年我们才能再见了。
It was three days before he came back. 他三天后才回来。
Before she could move, she heard a loud noise, which grew to a terrible roar. 她还没有来得及动弹，就听见有很响的声音，接着就成了可怕的隆隆轰鸣声。
Before they reached the house, a new great wave came, sweeping down trees, and sweeping them down too. 他们还没到屋子，又一个巨浪打来，冲倒了树，也冲倒了他们。
You should be a pupil before you become a teacher. 要当老师，先作学生。
You should do it before it is too late. 趁现在还不算太晚，你应该赶快做它。
1.it was（not）/had done＋一段时间＋before（vt-ed）…＂还要过多久才……（不多久就……了）＂
It was not long before he returned to Beijing. 不久他就回到北京。
It was long before he married Wei Fang. 过了很久他才娶魏芳。
2.it will（not）be＋一段时间＋before（一般式）… ＂还要过多久才……（不多久就……了）＂
It will be long before he goes abroad. 要过很久他才出国。
3.there is +一段时间+to go（=left）＋before（一般式）… ＂在……之前＂
4.long before ＂不久前＂, 用于一般过去时和完成时中；before long = soon/not long after ＂不久后＂，用于一般将来时和一般过去时中。
1.We need to get to the root of the problem ______________ we can solve it.
- while B. after C. before D. as
2.It ________ long before we ________ the result of the experiment.
aA.will not be；will know B. is；will know
C.will not be；know D. is；know
【答案解析】句意：不会过很长一段时间我们就会知道实验结果。应使用It was not long before的创新句型It will not be long before，before引导时间状语从句时，从句应用一般现在时代替一般将来时。
2.Scientists say it may be five or six years ________ it is possible to test this medicine on human patients.
A.since B. after C. before D. when
【答案解析】该句型也是It was not long before的创新句型。句意：科学家说也许再有5年时间这种药就可以在人类身上做实验了。
考向三as soon as/once/directly/the instant等引导的时间状语从句
as soon as 是最常见的表示＂一……就……＂的从属连词，其他连词还有once（一旦），directly（老式英国英语），immediately（主要用于英国英语），instantly，the instant (that)，the minute(that) ，the moment(that)等，它们通常都可与as soon as换用。
As soon as we got home, the telephone rang. 我们一到家，电话就响了。
I recognized her immediately I saw her. 我一看见她就认出她来了。
Directly the teacher came in everyone was quiet. 老师一进来，大家就静了下来。*网
考向四 hardly…when/no sooner…than引导的时间状语从句
He had no sooner (no sooner had he) arrived home than he was asked to start on another journey. 他刚一到家，就又要他出另一次差。
★ hardly/barely/scarcely和no sooner置于句首时，从句要倒装。
No sooner had the words been spoken than he realized that he should have remained silent. 这些话刚一出口，他就意识到自己应该保持沉默。
We’ve never met since we graduated from the college. 大学毕业后我们就再没见过面。
Great changes have taken place since you left. 你走了以后，这里发生了巨大的变化。
1.（2017·天津卷·完形填空）She had been talking to her mother about the lives of homeless people 42 they first saw the homeless man.
- since B. unless C. although D. as
2.I have heard a lot of good things about you I came back from abroad.
- since B. until C. before D. When
Donald will remain in college until (till) he finishes his Ph.D course. 唐纳德将留在学校直到完成他的博士学位课程。
I won’t go with you until (till) I finished my homework. 等我做完作业我才和你一起去。
not until 置于句首，主句要倒装。
Not until 4:00 in the morning can he fall asleep.
直到凌晨4点他才睡着。(He can’t fall asleep until 4:00 in the morning.)
Not until he returned did we have supper.
直到他回来我们才吃晚饭。 (We didn’t have supper until he returned.)
(2017·北京卷·单项填空)If you don’t understand something, you may research, study, and talk to other people _______ you figure it out.
- because B. though C. until D. since
【答案解析】A. because 因为 B. though尽管 C. until 直到 D. since自从。句意：如果你无法理解某个东西，你可能会去研究，学习并和他人探讨直到你解决为止，根据句意可知选用until“直到”，选C。
考向七each time/every time等引导的时间状语从句
这类连词主要有every time(每次)，each time(每次)，(the) next time(下次)，any time(随时)，(the) last time(上次)，the first time(第一次), by the time(当……的时候)。如：
You can call me any time you want to. 你随时都可以给我打电话。
Each time I went there, I saw him working. 我每次去那儿都看见他在工作。
Every time I see her I’ll think of it. 每次我看到她，我就想起这事。
Next time you come in, please close the door. 下次你进来，请关门。
He didn’t tell me the last time I saw him. 我上次见到他时他没告诉我。
The first time I heard about the firm closing down was when George told me.
By the time, he was taken to the hospital he was nearly dead.
注意：every time, each time, any time前不用冠词，(the) next time, (the) last time中的冠词可以省略，而the first time中的冠词通常不能省略。
1.It was 3 in the morning ___________ the earthquake happened. Hundreds were killed, with a lot ___________ in the collapse.
2.__________ it comes to traffic rules, I often come across such cases __________ the local drivers obviously know them but won’t follow them.
3.Every time __________ they met, they would talk excitedly for several hours about the schoolmates and incidents __________ they still remembered in the primary school.
A.that；who and which B.when；that
4.Many people have heard of the ＂brain drain＂. This is ___________ happens __________ people with good skills and a good education move to other country for study or work, often at great expense to their home countries.
5.—Glad to see you, Kate.
—Oh, my God. It’s been 20 years ___________ we last saw each other.
6.He smiled politely ____________ Mary apologized for her drunken friends.
7.___________ the poem a second time, the meaning will become clearer to you.
A.Having read B.While reading
C.If reading D.When you read
8.The police set about arresting the suspect ___________ they found enough evidence to prove him guilty.
A.immediate B.as long as
C.the moment D.as far as
9.The police had to employ force ___________ the crowd got out of control.
A.the instant B.at the instant
C.in an instant D.for an instant
10.If individuals are awakened ___________ they begin a dream phase of a sleep, they are likely to become irritable even though their total amount of sleep has been sufficient.
A.as if B. now that
C.each time D.first time when
Eating organic food will not make you healthier, according to researchers at Stanford University, although it could cut your 1 (expose) to pesticides(杀虫剂).They looked at more than 200 studies of the content and 2 (associate) health gains of organic and non-organic food. Overall, there 3 (be) no difference in the nutritional content, although organic food was 30% less likely 4 (contain) pesticides.
The researchers looked at 17 studies comparing people who ate organic food 5 those who did not and 223 studies 6 compared the levels of nutrients, bacteria and pesticides in various food. However, none of the human studies ran for longer than two years, 7 (make) conclusions about long-term 8 (outcome) impossible. And all of the available evidence was 9 (relative) weak and variable, which the researchers said was unsurprising because of all the different variables.
Dr Crystal Smith-Spangler, the lead researcher, said “Some believe organic food is always healthier and more nutritious. But as 10 matter of fact there isn’t much difference between organic and conventional food, if you’re an adult and make decisions based simply on your health.”
1.(2016·天津)______ the average age of the population increases, there are more and more old people to care for.
A.Unless B. Until
C.As D. While
2.（2016·浙江）______online shopping has changed our life , not all of its effects have been positive.
A.Since B. After
C.While D. Unless
3.(2015·天津) We need to get to the root of the problem______ we can solve it.
A.while B. after
C.before D. as