不遗余力 (bù yí yú lì) — to spare no effort; to do one's utmost

Definition

不遗余力 (bù yí yú lì) is a chengyu (four-character idiom) meaning 'to spare no effort' or 'to go all out.' It emphasizes putting all available energy into something without holding back, and is often used in formal or written contexts. As a fixed expression, it can be placed before a verb with 地 (de), or used as a predicate on its own. The literal image is 'not leaving behind any remaining strength.'

f.e.

to spare no effortto do one's utmost

Examples

不遗余力。
Tā bù yí yú lì de bāngzhù yǒu xūyào de rén.
He spares no effort in helping those in need.
不遗余力。
Gōngsī duì zhège wèntí bù yí yú lì de diàochá.
The company investigates this problem with utmost effort.
不遗余力。
Lǎoshī bù yí yú lì de jiào xuéshēng zhīshi.
The teacher teaches students knowledge with all their effort.

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