下面举例说明il-，im-和ir-的构词特点。 

illegal [ il- (in-) = not 不；legal a. 合法的→]a. not lawful 不合法的，非法的 / Driving faster than the speed limit is illegal. 超速行车是违法的。

illegality n .非法；违规 

illegalize v. 使非法；宣布为非为

imbalance [ im- (in- ) = lack of 不；balance n. 平衡→]n. lack of balance 不平衡 / The trade imbalance in the country has lessened. 该国的贸易不平衡已经减少。

immortal [ im- (in-) = not 不；mortal a. 终有一死的→]a. not mortal; living forever 不朽的；永存的 / The fame of Shakespeare should be immortal. 莎士比亚的声誉永存。

immortality n. 不朽，永存；不灭的声望 

immortalize v. 使不朽，使不灭

imprudent [ im- (in-) = not 不；prudent a. 谨慎的→]a. not prudent; heedless 轻率的；鲁莽的 / It is imprudent to run into something without thinking what may happen. 不考虑可能发生的结果而匆忙行事是很轻率的。

imprudence n. 轻率，鲁莽

irregular [ ir- (in-) = not 不；regular a. 不规则的→]a. not regular; not according to rule 不规则的，无规律的 / He is irregular in his attendance at school. 他不时旷课。

irregularity n. 不规则，无规律