連詞解釋 because,for,since,as,的區(qū)別

because語氣強,表示客觀必然原因：
he is absent, because he is ill. 因為生病，所以他沒來。
比較:he is absent, for he is busy. （“生病”是“缺席”的必然原因，“忙”不是必然原因。）

for 語氣輕,表示非客觀必然的原因,是主觀可改變結(jié)果的原因,甚至是猜測可能的原因:
he must be ill, for he is absent. “缺席”不一定是“生病”，只是交流猜測。
for 不能放句首,它是并列連詞.

since,as 都是不講自明的原因,是已知的原因.
since i am a boy, let me carry the case.
as you don‘t feel well,you had better stay at home.

1.我不進去了,因為我爸爸在里面. i won‘t go in .for my father is there.
2.昨晚一定是下雨了,因為地很濕. it must have rained last night,for the ground is web.
3.地是濕的,因為昨晚下雨了. the ground is wet, because it rained last night.
4.因為不高興,他不想出去了. he diden‘t wanted to go out,for he was unhappy.
5.既然你工作忙，你就不必跟我們一道去了。 since/as you are busy, you had better not go with us.
6.他付給我比別人少的錢,因為我是個女的. he paid me less than the others, for i‘m female.
7.他付給我比別人少的錢,僅僅因為我是個女的. he paid me less than the others, only because i‘m female.
8.既然大家都在這,我們開始開會吧. since everybody is here,let‘s begin our meeting.

二.when,while,as引導(dǎo)時間狀語時的異同.
when,表示時間點,時間段都可以.如狀語是短暫動作時,多用when,是時間段時則三個連詞都可以.
when/while/as i was walking in the street,i met a friend of mine.

只能用when 的句型:
1.放句中,主句是進行時,從句是短暫動作,表示這時突然
i was reading in the room, when a girl shouted for help.我正在房間看書，這時突然聽到有一個女孩喊救命！

2.從句是短暫動作:when i got up, i heard the bell ring. 當(dāng)我起床的時候，我聽見鈴響了。

只能用while的句型:
1.表示對立予盾的對比，這時while相當(dāng)于but。
i am poor while you are rich.我很窮，你卻很富有。
tom is strong,while john is weak. 湯姆很強壯，而約翰很瘦弱。

2.表示“趁著還來得及的時候,趕快....
趁熱打鐵.strike while it is hot.
趁著老師還在教室,你趕快去問他吧. you should go to ask the teacher while he is still in.

只能用as的句型:
1.一邊....一邊...穩(wěn)定的動作當(dāng)從句,不穩(wěn)定的動作當(dāng)主句
他一邊洗澡一邊吹口哨. he whistled as he had a bath.
我一邊看書一邊聽音樂. i listened to music as i read.

2.正如....所知道,預(yù)料的一樣.... as 在此是關(guān)系代詞,不能用which代替.
正如眾所周知的一樣,地球是圓的. as everybody can see,the earth is round.
正如我們預(yù)料的那樣，他失敗了。he failed as we had expected.
正如我們所預(yù)料的一樣,中國足球隊贏了印尼. as we had expected,chinese football team betean indian

3.隨著時間的發(fā)展,某事變得......
as thirty years passed by,my mother‘s hair became gray. 三十年過去了，媽媽的頭發(fā)成了銀色。
as morden industry develops,more and more waste produces. 隨著工業(yè)的發(fā)展，垃圾制造得越來越多。
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