once

O 開頭單詞四級詞匯專八核心詞雅思備考詞托福詞匯高考詞匯詞源字典

常用用法

conj. (連詞)

once用作連詞時可引導時間狀語從句和條件狀語從句。用于前者時意為“一旦…就…”,所引導的從句多很短; 用于后者時意為“只要”,這種條件從句似帶有時間條件的含意。
once引導的從句中有些部分可以省略。

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詞語辨析

n. (名詞)

at once, directly, immediately, instantly, presently, right away

這組詞(組)的共同意思是“立即”“馬上”。其區(qū)別在于:
1.at once主要指動作迅速,但中間多有一段距離,且at once比immediately意味更強。例如:
I'm leaving for Rome at once.我馬上去羅馬。
He gave orders for the work to be started at once.他下令立即開始那項工作。
2.immediately側(cè)重指時間“緊接著”。例如:
I came immediately after I'd eaten.吃過飯我立即就來了。
Please close your books immediately and answer these questions.請立即合上書,回答這些問題。
I left immediately when the clock struck twelve.鐘剛打12點我就離去了。
3.right away經(jīng)常出現(xiàn)在美式英語中。例如:
I'll do it right away.我立即去辦。
He had written down a list of things to do right away.他已寫下須立即做的事情。
Don't expect them to approve of the design right away.不能期望他們馬上批準這項設計。
4.instantly也是指動作迅速,但它更強調(diào)的是同時發(fā)生,中間有很短的距離或無距離。例如:
The electrician went instantly in answer to the phone call.電工師傅一接到電話馬上就去了。
He was killed instantly in a car accident.在車禍中,他當場死亡。
5.directly強調(diào)“直接地”,多與“迂回繞過”相對。例如:
Whether he sailed directly across the bay or coasted round it is uncertain.他是徑直駛過海灣,還是沿海岸迂回繞過的,現(xiàn)在還無法確知。
6.presently強調(diào)過一會再去做某事。例如:
I will do the dishes presently, but I want to finish the story first.我過一會去洗碟子,不過我想得先看完這篇故事。

at once, soon

這兩個詞(組)的區(qū)別是:soon表示“不久”“很快”,強調(diào)時間很短; at once表示“馬上”“立刻”,強調(diào)動作隨即發(fā)生。例如:
He soon became active in the class.他在班上很快就變得活躍起來。
When I heard the knock,I opened the door of the room at once.我聽到敲門聲馬上就把房門打開了。

once，as soon as

兩者均為從屬連詞，引導時間狀語從句，都表示主句的動作緊跟在從句的動作之后發(fā)生。
once除表時間外，還表示條件，一般譯作“一旦......就......”。
as soon as強調(diào)的只是時間，譯作“剛......就......”或“一......就......”。

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