· in a jiffy不大一会儿
=in a moment, right away. at once
i'll be with you in a jiffy.
· have ( a case of ) the jitters忐忑不安
the new teacher had a case of jitters when he first stood in front of the class.
· keep up with the joneses与别人比阔，与别人攀比
he likes keeping up with the joneses.
· get a kick out of doing something从……得到很大的乐趣
he gets a kick put of racing.
· take kindly to something/someone愿意接受
don't you feel that people in the lab don't take kindly to a nosy reporter?
· kill someone with kindness好得让人受不了
the old lady almost killed me with kindness when i lived at her home.
· parade one's knowledge买弄学问
he is a well-learned man, bit he never parades his knowledge.
· be at large逍遥法外（也可以形容动物不受约束）
the murderer was still at large. the victim's parents was determined to find enough evidence to sue him to court.
· rest on one's laurels故步自封，吃老本
you are sure to be lagged behind if you rest on your laurels.
· turn over a new leaf洗心革面
the juvenile delinquent promised that he would turn over a new leaf if he could be given lenient punishment.
· have a hollow leg（喝酒）海量
the best man has a hollow leg. he drinks a lot instead of the bridegroom.
· pull someone's leg开某人的玩笑
never ever pull his leg. he is a man without a sense of humor. he takes everything seriously.
· keep someone at arm's length与某人保持距离
my boss is my uncle. in order to avoid unnecessary misunderstanding, i'd better keep him at arm's length in company.
· let someone down使某人失望
joe really let me down by having broken his promises for several times.
· can't for the life of one怎么……也不行
i thought i could recite my speech backwards, but when i stood in front of the audience, i couldn't for the life of me remember what to say.
· air one's linen in public家丑外扬
the wife was often beaten by her husband, but she never told others. she didn't want to air her linen in public.