2011年全國(guó)公共英語(yǔ)五級(jí)考試（pets5）的考試時(shí)間為6月4日，距離考試還有不到兩個(gè)月。為了幫助大家提高考試成績(jī)，現(xiàn)在給大家準(zhǔn)備了考試相關(guān)的語(yǔ)法指導(dǎo)，供大家參考。
8 比較while, when, as
1）as, when 引導(dǎo)短暫性動(dòng)作的動(dòng)詞。例如：
Just as / Just when / When I stopped my car, a man came up to me. 我一剎車，有一個(gè)人向我走來(lái)。
2）當(dāng)從句的動(dòng)作發(fā)生于主句動(dòng)作之前，只能用when 引導(dǎo)這個(gè)從句，不可用as 或 while。例如：
When you have finished your work, you may have a rest. 趕完活后，你可以休息一下。
3）從句表示"隨時(shí)間推移"連詞能用as，不用when 或while。例如：
As the day went on, the weather got worse. 日子一天天過去，天氣越變?cè)綁摹?BR> 返回狀語(yǔ)從句目錄
9 比較until和till
此兩個(gè)連詞意義相同。肯定形式表示的意思是"做某事直至某時(shí)"，動(dòng)詞必須是延續(xù)性的。否定形式表達(dá)的意思是"直至某時(shí)才做某事"。動(dòng)詞為延續(xù)性或非延續(xù)性都可以。正確使用這兩個(gè)連詞的關(guān)鍵之一就在于判斷句中的動(dòng)詞該用肯定式還是否定式。肯定句：I slept until midnight. 我一直睡到半夜時(shí)醒了。
Wait till I call you. 等著我叫你。（在肯定句中可用before代替。例如 Let's get in the wheat before the sun sets.）
否定句：She didn't arrive until 6 o'clock. 她直到6點(diǎn)才到。
Don't get off the bus until it has stopped. 公共汽車停穩(wěn)后再下車。
I didn't manage to do it until you had explained how. 直到你教我后，我才會(huì)做。
區(qū)別：1）until可用于句首，而till通常不用于句首。例如：
Until you told me, I had heard nothing of what happened. 直到你告訴我以前，出了什么事我一點(diǎn)也不知道。
2）until when 疑問句中，until要放在句首。例如：
---Until when are you staying? 你呆到什么時(shí)候？
--- Until next Monday. 呆到下周一?！?BR> 注意：否定句可用另外兩種句式表示。
1）Not until…在句首，主句用倒裝。例如：
Not until the early years of the 19th century did man know what heat is. 直到19 世紀(jì)初，人類才知道熱為何物。
Not until I began to work did I realize how much time I had wasted. 直到工作，才認(rèn)識(shí)到我已蹉跎了幾多歲月。
2）It is not until… that… 。例如：
It was not until I began to work that I realized how much time I had wasted.
10 表示"一…就…"的結(jié)構(gòu)
hardly/scarcely…when/before, no sooner…than 和as soon as都可以表示"一…就…"的意思。例如：
I had hardly / scarcely got home when it began to rain. 剛回家，就下起雨來(lái)了。
I had no sooner got home than it began to rain.
As soon as I got home, it began to rain.
注意：如果hardly, scarcely 或no sooner置于句首，句子必須用倒裝結(jié)構(gòu)。例如：
Hardly / Scarcely had I got home when it began to rain.
No sooner had I got home than it began to rain.
8 比較while, when, as
1）as, when 引導(dǎo)短暫性動(dòng)作的動(dòng)詞。例如：
Just as / Just when / When I stopped my car, a man came up to me. 我一剎車，有一個(gè)人向我走來(lái)。
2）當(dāng)從句的動(dòng)作發(fā)生于主句動(dòng)作之前，只能用when 引導(dǎo)這個(gè)從句，不可用as 或 while。例如：
When you have finished your work, you may have a rest. 趕完活后，你可以休息一下。
3）從句表示"隨時(shí)間推移"連詞能用as，不用when 或while。例如：
As the day went on, the weather got worse. 日子一天天過去，天氣越變?cè)綁摹?BR> 返回狀語(yǔ)從句目錄
9 比較until和till
此兩個(gè)連詞意義相同。肯定形式表示的意思是"做某事直至某時(shí)"，動(dòng)詞必須是延續(xù)性的。否定形式表達(dá)的意思是"直至某時(shí)才做某事"。動(dòng)詞為延續(xù)性或非延續(xù)性都可以。正確使用這兩個(gè)連詞的關(guān)鍵之一就在于判斷句中的動(dòng)詞該用肯定式還是否定式。肯定句：I slept until midnight. 我一直睡到半夜時(shí)醒了。
Wait till I call you. 等著我叫你。（在肯定句中可用before代替。例如 Let's get in the wheat before the sun sets.）
否定句：She didn't arrive until 6 o'clock. 她直到6點(diǎn)才到。
Don't get off the bus until it has stopped. 公共汽車停穩(wěn)后再下車。
I didn't manage to do it until you had explained how. 直到你教我后，我才會(huì)做。
區(qū)別：1）until可用于句首，而till通常不用于句首。例如：
Until you told me, I had heard nothing of what happened. 直到你告訴我以前，出了什么事我一點(diǎn)也不知道。
2）until when 疑問句中，until要放在句首。例如：
---Until when are you staying? 你呆到什么時(shí)候？
--- Until next Monday. 呆到下周一?！?BR> 注意：否定句可用另外兩種句式表示。
1）Not until…在句首，主句用倒裝。例如：
Not until the early years of the 19th century did man know what heat is. 直到19 世紀(jì)初，人類才知道熱為何物。
Not until I began to work did I realize how much time I had wasted. 直到工作，才認(rèn)識(shí)到我已蹉跎了幾多歲月。
2）It is not until… that… 。例如：
It was not until I began to work that I realized how much time I had wasted.
10 表示"一…就…"的結(jié)構(gòu)
hardly/scarcely…when/before, no sooner…than 和as soon as都可以表示"一…就…"的意思。例如：
I had hardly / scarcely got home when it began to rain. 剛回家，就下起雨來(lái)了。
I had no sooner got home than it began to rain.
As soon as I got home, it began to rain.
注意：如果hardly, scarcely 或no sooner置于句首，句子必須用倒裝結(jié)構(gòu)。例如：
Hardly / Scarcely had I got home when it began to rain.
No sooner had I got home than it began to rain.