乐此不疲的英文：
delight in a thing and never get tired of it

参考例句：

To delight in a thing and never get tired of it
乐此不疲

He is never bored with football.
对于足球，他乐此不疲。

He had a decided propensity for bullying; derived no inconsiderable pleasure from the exercise of petty cruelty
他素有恃强凌弱的癖好，而且乐此不疲。

Forget not yet the tried entent Of such a truth as I have meant; My great travail so gladly spent, Forget not yet
别忘了我曾对你怀有真情，忠贞不渝，苦苦追求，乐此不疲。别忘了

delight是什么意思：
n. 高兴；快乐；使人高兴的东西或人
v.（使）愉快，高兴；以某事物为乐；喜好某事物

She delights in her work.
她喜爱她的工作。

Delight shone in her eyes.
她的眼中闪现着欢乐。

She was a phantom of delight.
她是欢乐的化身。

thing是什么意思：
n. 东西；事物；衣物；财物；形势，情况；事业；家伙；事情

These things will happen.
这种事总要发生的。

These are things that were proposed as reasonable things to do.
这些被当作合理的事情提议出来。

Example is not the main thing in influencing others. It is the only thing.
榜样是影响他人的一样东西，但它不是主要的。

never是什么意思：
adv. 从不，不曾；决不

to dream of a never - never land where everyone is rich
梦想中的理想之国，那里人人富有

Never be haughty to the humble. Never be humble to the haughty.
对谦卑的人切勿傲慢，对傲慢的人切勿谦卑。

China will never seek hegemony and never go in for expansion
中国永远不称霸，永远不搞扩张。