when除了用來(lái)引導(dǎo)主語(yǔ)從句、賓語(yǔ)從句、時(shí)間狀語(yǔ)從句、表語(yǔ)從句和定語(yǔ)從句,可以為副詞、連詞、代詞,根據(jù)不同用法而定.
下面是when的不同詞性用法,差別還是挺大的,看下例句,就能感受出來(lái).
語(yǔ)法沒(méi)有為什么,就是這么用的,應(yīng)用熟練就好了.
adv副詞,conj連詞 pron 代詞
when:
(1) adv.什么時(shí)候,何時(shí) at what time
[例句]
When can you come to see me?
你什么時(shí)候來(lái)看我?
(2) adv.是…時(shí)候at which;on which
[例句]
Please tell me when we'll have the meeting.
請(qǐng)告訴我我們什么時(shí)候開(kāi)會(huì).
(3) adv.在…的時(shí)候 at or during which
[例句]
How I regretted the days when I had played and should have studied!
我多么懊悔我本該好好學(xué)習(xí)卻玩掉了的那么多的日子!
(4) adv.那時(shí) but at that moment
[例句]
It happened on a day in November when the weather was very wet and cold.
這事發(fā)生在十一月的一天,那時(shí)天氣又潮濕又寒冷.
We were about to start,when it began to rain.我們剛要出發(fā)時(shí)開(kāi)始下雨了.
(5) conj.當(dāng)…時(shí) at the time when
[例句]
It happened when I was living in the country.事發(fā)生在我住在農(nóng)村的時(shí)候.
It was raining when we arrived.我們到達(dá)時(shí),天正下著雨.
(6) conj.一…就 immediately after
[例句]
When I had finished dinner I went to bed.
我吃完飯就睡覺(jué)了.
Let us set out when the sun has risen.太陽(yáng)一出來(lái),我們就動(dòng)身.
(7) pron.（關(guān)系代詞）那時(shí)
which time
[例句]
I came here in 1949,since when I have been engaged in this work.
我1949年到這里,從那時(shí)起我就擔(dān)任這項(xiàng)工作.
We came a week ago,since when the weather has been bad.
我們?cè)谝恍瞧谇皝?lái)此,從那時(shí)起天氣就一直不好.
(8) pron.（疑問(wèn)代詞）什么時(shí)候
what time
[例句]
Since when have you been here?你從何時(shí)起在此地?
Until when can you stay?你能呆到什么時(shí)候?我按我的理解來(lái)吧，例句的核心是：police想要知道what（就是you enter the room），這句是個(gè)what引導(dǎo)的主語(yǔ)從句，這個(gè)what(you enter the room) 在句子中充當(dāng)賓語(yǔ)，when這邊做連接副詞，修飾的是從句部分，即為you enter the room。做副詞就像你說(shuō)的，在句中是有作用的，你判斷他是副詞前，必須對(duì)這個(gè)句子結(jié)構(gòu)進(jìn)行剖析，看是否是主從句，成分如何等等，而不是一開(kāi)始糾結(jié)這個(gè)when是什么詞性，句子結(jié)構(gòu)分析好了，自然知道這個(gè)when在句中到底起不起作用。詞語(yǔ)跟著句子走，有時(shí)候這個(gè)when究竟是什么詞性并不重要，重要的是when這個(gè)詞對(duì)于整個(gè)句子發(fā)揮了什么作用，連詞也好副詞也罷，幫助理解句意就是他們的重點(diǎn)。而你看when做連詞的時(shí)候，連詞就是個(gè)連接作用，拿我的幾個(gè)例句來(lái)說(shuō)吧：(5) conj. 當(dāng)…時(shí)at the time when[例句]It happened 這是一個(gè)獨(dú)立句子【when】 I was living in the country. 這又是一個(gè)獨(dú)立句子兩個(gè)句子都很完整，沒(méi)有誰(shuí)充當(dāng)誰(shuí)的成分It was raining 這是一件事【when】 we arrived又是另一件事兩個(gè)句子在發(fā)生上有聯(lián)系，但是對(duì)于句子本身，沒(méi)有互相充當(dāng)成分。(6) conj. 一…就 immediately after[例句]【W(wǎng)hen】 I一 had finished dinner就 I went to bed.兩個(gè)事情是在發(fā)生有時(shí)間先后的聯(lián)系，所以用when來(lái)連接，并不是其修飾作用Let us set out 【when】 the sun has risen.太陽(yáng)一出來(lái)，我們就動(dòng)身。同上純手打了N久……自己理解的，參考了一些資料，我也幫你問(wèn)別人了，太晚了還沒(méi)回我短信……求可憐可憐我！??！希望如果不清楚或者錯(cuò)誤，繼續(xù)追問(wèn)哈~對(duì)于我自己也是一個(gè)幫助。________________________老師回我短信了在你的例句中，你把when放在you enter the room的后面，會(huì)發(fā)現(xiàn)這里when相當(dāng)于一個(gè)介詞短語(yǔ)，由此判斷when又是一個(gè)副詞,又因?yàn)楦鶕?jù)上文，when祈禱了鏈接作用，所以稱為連接副詞。另舉個(gè)例子，come here when you are free，這里的when如果改成一個(gè)介詞短語(yǔ)（如at what time）整個(gè)句子就不成立了！所以是連詞而不是副詞?！恢缼偷接H沒(méi)，一大早的回你了~我還有事，先撤了！晚上再來(lái)看。