連詞用于引導(dǎo)從句以形成句子的一部分或修飾句子的構(gòu)成要素的叫作從屬連詞.由從屬連詞所引導(dǎo)的句子叫從句,而含有從句的句子叫作復(fù)合句.
連詞是連接單詞,短語,從句或句子的一種虛詞.
從屬連詞這種連詞是用以引導(dǎo)名詞性從句和狀語從句的.
在英語詞類中,連接詞可說是最容易掌握的一種.
從結(jié)構(gòu)上說,英語連接詞分兩大類：并列連詞（coordinating conjunctions）和從屬連詞（subordinating conjunctions）.
并列連詞連接兩個或兩個以上地位平等的字、詞組或分句.例如：(1) Air and water are indispensable to me.
(2) She likes going out with friends or playing outdoor games.
(3) Most workers have a good income,so they look very happy.
從屬連詞連接兩個或兩個以上的分句,形成復(fù)雜句中的從屬分句.例如：
(4) He said that he did not want to go .
(5) Many things have happened since I last saw him.
(6) You may come if you want to.
上述連詞的用法,看起來不難,但錯誤也難免.下面是些好例子：
(1) This book may be used both as a text as well as a reference book.
這里的“as well as”和“both”不能搭配,應(yīng)該將“as well ”改為“and”,使“both.and.”變成關(guān)聯(lián)連詞（ correlative conjunction）
(2) He not only speaks Mandarin but also English.
這里的“not only”應(yīng)該移到“speaks”后面,使這個動詞兼顧兩個等立賓語：“Mandarin”和“English”.
(3) Although he is fat,but he is very weak.
英語里的“although”和“but”是不見面的 ,因此這句里的“ but”要去掉,不然“although”就要出來.
(4) Jim is not so strong like you.
這里的“not so”必須和“as”連成一體；介詞“l(fā)ike”是不適宜的.
(5) No sooner had we reached our destination,they left.
"No sooner"必須和"than" 配成關(guān)聯(lián)連詞,把"than" 省掉是不對的,應(yīng)該補上：
No sooner had we reached our destination than they left.
這句子的意思也可透過“as soon as”反映出來：
“As soon as we reached our destination,they left.”
(6) I took a taxi and which took me to the station.
這里的并列連詞“and”是多余的,必須去掉.如果要保留“and ”也可,但是形容詞分句里的關(guān)系代詞“Which”要改成主語“it” ,使整個句子變成并列分句如下：
I took a taxi and it took me to the station.
(7) My friend came up to me and held my hand,said good-bye excitedly.
這里的“and”應(yīng)該用來連接最后兩個謂語才對：
My friend came up to me,held my hand,and said good-bye excitedly.
不然,就要把“said”改成“saying”.
My friend came up to me and held my hand,saying good-bye excitedly.