這種方法科學合理，記憶牢固并且迅速，常用前綴、后綴可前往查看。詞匯的前綴一般修飾或者改變單詞的意思，詞匯的后綴一般改變單詞的詞性。為了廣大考生更好更快的記憶單詞，對考研英語詞匯常見的反義否定前綴進行了匯總，希望對2018年考研的廣大考生有所幫助。

1. dis-(加在名、形、動詞前)表示“不，不再”

disadvantage n. 不利，不利條件;

E.g. Depression is the third thing that works to my patients' disadvantage.

抑郁是威脅我的病人健康的第三大殺手。

disappear. v. 消失

E.g.He saw something dark disappear behind the curtain of leaves.

他看到一個黑漆漆的東西從濃密的樹葉后消失了。

disconnect. v. 分離

E.g.You should disconnect the wireless set before you make adjustments inside it.

你應先拔掉無線電插頭,再做內部調整。

2. di-,dif-, dis-：away，negative否定，分開，不

distrust. v. 不信任, 懷疑

E.g.What he saw there left him with a profound distrust of all political authority.

他在那兒的所見讓他對一切政治當局產(chǎn)生了一種深深的不信任感。

disassemble v. 拆開

E.g.We had to completely disassemble the engine to find the problem.

我們只好把發(fā)動機全部拆開以尋找故障原因。

differentiate v.區(qū)分

E.g.A child may not differentiate between his imagination and the real world.

兒童可能無法將自己的幻想與真實世界區(qū)分開來。

3. il-：(加在以“l(fā)”開頭的詞前)表示“不”

illiterate n. 文盲;

E.g.Many senior managers are technologically illiterate.

許多高級經(jīng)理都對技術知之甚少。

illegitimate a. 非法的

E.g.The election was dismissed as illegitimate by the opposition.

反對黨以不合法為由拒絕接受選舉結果。

4. im-，in-(加在字母m，b，p之前)not，in，into否定，加強或引申意義

impracticable行不通的

E.g.Such measures would be highly impracticable and almost impossible to apply.

這樣的措施非常不切實際,幾乎不可能付諸實施。

invisible不可見的;

E.g.Parents fear they might overstep these invisible boundaries...

父母擔心他們可能會逾越這些無形的界限。

irrational不合理的;

E.g. His behavior was becoming increasingly irrational.

他的行為變得越來越不理智了。

5. mal- bad，badly：惡，不良

maltreat虐待;

E.g.He said that he was not tortured or maltreated during his detention...

他說自己在押期間并未遭受拷問和虐待。

malnutrition營養(yǎng)不良

E.g.Infections are more likely in those suffering from malnutrition.

營養(yǎng)不良的人更有可能被傳染。