de-是個(gè)用法較為復(fù)雜的前綴。它原是個(gè)拉丁介副詞，只出現(xiàn)在拉丁或法語(yǔ)借詞中。de-依附在詞根前，表示dwon(from)或away(from)的意思，有時(shí)則表示對(duì)詞根的強(qiáng)調(diào)，有completely 的意思。后來(lái)，de-被英語(yǔ)所同化，變成一個(gè)相當(dāng)活躍的派生前綴。它可以加在動(dòng)詞或名詞之前生成否定意義的動(dòng)詞。當(dāng)它與動(dòng)詞結(jié)合時(shí)，基本意思是to undo,表示“做（與原動(dòng)詞）相反的動(dòng)作”。當(dāng)它與名詞結(jié)合時(shí)，基本意思是to make down or away,表示“降低，剝離，取走”等動(dòng)

作，下面，我們按照de-的構(gòu)詞功能，分別介紹。

先觀察由de-與詞根結(jié)合的幾個(gè)具有代表性的例子。

1.decline [de- = down 下；clin = to bend 彎；-e → " to bend down 彎下去"→]
v. 下傾
舉例：The road declines at the turn. 到拐彎處路轉(zhuǎn)下坡了。

2.decrease [de- = down 下；creas = to grow 變得]
v. 減少；減小
舉例： Hunger decreases as one eats. 吃東西時(shí)饑餓感就減少了。

3.debar [de- = away 外；bar = to shut 關(guān)→]
vt. 排除；阻止
舉例：He was debarred from club membership because of the scandal. 因?yàn)槟羌舐?，他被俱?lè)部拒之門(mén)外。

4.detract [de- = away 離；tract = to draw 抽→]
v. 減損；貶低
舉例：The ugly frame detracts from the beauty of the picture. 難看的畫(huà)框影響了這幅的美麗。

最后介紹de-作為動(dòng)詞性前綴與名詞結(jié)合的例子。

1.declass [de- = to make down 使向下；class n.階級(jí)→]
vt. 使降低或失去社會(huì)地位
舉例：The baron had some working-class relatives,so he was declassed. 男爵有一些屬于勞工階層的親屬，因此他的社會(huì)地位就降低了。

2.degrade [de- = to make down 使向下；grad n.級(jí)別 →使某人級(jí)別下降]
vt. 使降低，貶黜
舉例：The sergeant was degraded to private for disobeying orders. 那中士因?yàn)椴环拿畋唤禐槭勘?br>
3.debark [de- = to get away from 從...離開(kāi)；bark n.船 →]
v. 下（船、飛機(jī)等），上岸，登陸
舉例：After the passengers debarked in port,the captain debarked his crew. 旅客上岸后，船長(zhǎng)打發(fā)手下人下船。