2020考研英語常用詞匯之：as的用法

　　六月份了，暑期將至，考研英語復(fù)習(xí)首先對于基礎(chǔ)常識要有了解，復(fù)習(xí)之初最好把這些都搞明白，然后有針對性的開展復(fù)習(xí)，英語復(fù)習(xí)必然從背單詞開始。下面分享了考研英語常用詞匯：as的用法總結(jié)，希望對大家有所幫助。

　　一、as作為介詞的用法：

　　1.表示“作為”，“以……身份”。例如：Tom found a job as a teacher.

　　2.表示“像…一樣”，例如：They were all dressed as policeman.

　　二、as作為副詞的用法：

　　1.表示“與…等同”。如：They don’t have as many boxes.

　　2.表示“像，如”。如：As before, he remained slient.

　　三、as可作從屬連詞，作關(guān)系副詞時可以引導(dǎo)比較、時間、原因及方式等四種狀語從句，作關(guān)系代詞時可以引導(dǎo)定語從句：

　　(一)as作從屬連詞引導(dǎo)狀語從句時：

　　1.表示“在…期間，當(dāng)…的時候”引導(dǎo)時間狀語從句，要注意其與when、while的用法區(qū)別。as與when，while都是引導(dǎo)時間狀語從句的從屬連詞，含義都是“當(dāng)……的時候”。但它們有區(qū)別：用when時，從句的動作可以與主句的動作同時發(fā)生，也可以先于主句的動作發(fā)生;用while時，從句的動作為一過程，主句動作與從句動作同時進(jìn)行或在從句動作過程中發(fā)生;用as時，主句和從句的動作同時發(fā)生，具有延續(xù)的含義。

　　下列情形時,只用as，而不用when或while。

　　1)表示兩個同步發(fā)生的動作或行為，意思是“隨著…的發(fā)展”。如：

　　As time went on, she became more and more worried.

　　As we get older, we become more and more interested in everything.

　　2)用于表示同一個人的兩種動作交替進(jìn)行，指“一邊…一邊”。如：

　　The girl sings as she goes to supermarket.

　　He looked behind occasionally as he went forward in the forest.

　　3)接在名詞后面表示某一個年齡段時。如：

　　As a young man, he was active in answering questions.

　　4)表示兩個短暫行為或事情幾乎同時發(fā)生。如：

　　I watched her as she read the book.

　　I thought of it just as you opened your mouth.

　　when作“當(dāng)……的時候”解,可以指較短的時間，也可指一段時間。如：

　　It was raining when he arrived at the factory.

　　When I was at college, I could speak several foreign languages.

　　while常表示一段較長的時間或一個過程,強調(diào)主句謂語動詞與從句謂語動詞同時發(fā)生。如：He was watching TV while his mother was cooking.

　　2.as作“既然”、“由于”解，引導(dǎo)原因狀語從句，常用來表示已為人們所知或顯而易見的原因或理由。與because，since相比，as一般放在句首，語氣較弱，較口語化。如：

　　As you’re not feeling well, you may stay at home.

　　As he wasn’t ready, we went without him.

　　3.as作“像”、“按照……的方式”解，引導(dǎo)方式狀語從句。如：

　　Leave things as they are.

　　Remember, you must do everything as I do.

　　4.表示“雖然，盡管”，引導(dǎo)讓步狀語從句，多在主句之前，且常用倒裝語序，模式為：adj. /adv. /n. /v.+as+主語+謂語+主句。如：

　　Young as he is, he knows much about electricity.

　　Try as he did, he failed again.

　　知識拓展：用于as…as或not / so/ as…as中，前一個as是副詞，后一個as是連詞，引導(dǎo)比較狀語從句。如：

　　They help the old as much as they can.

　　I don’t speak English as well as she does.

　　(二)as作從屬連詞引導(dǎo)定語從句時，表示“正如”：

　　1.引導(dǎo)限制性定語從句。如：

　　He isn’t the same person as he used to be.

　　I have never heard such story as he is telling.

　　I am not so strong a man as I was.

　　2.引導(dǎo)非限制性定語從句，修飾整個主句或主句的一部分，可在句首、句中、句末。如：He is very careful, as we all know.

　　As is well known, she has two sisters.

　　This machine, as might be expected, has stopped operating.

　　總之，通過以上的分析，我們對as的詞性和用法有了比較全面的理解和把握，這樣才能在實際的運用中做到心中有數(shù)，應(yīng)付自如。