竭力 (jié lì) means “try one's best”

More examples

居民们竭力保护当地的自然环境。jū mín men jié lì bǎo hù dāng dì de zì rán huán jìng

The residents are doing their best to protect the local natural environment.

All available strength is poured into one effort until the goal is reached.

尽力jìn lì: Do one's best to carry out a task or deal with a problem.
竭尽全力jié jìn quán lì: Use every bit of one's strength to complete a task.
全力以赴quán lì yǐ fù: Devote all one's energy to one task and pursue it wholeheartedly.

用尽全部力量去做某事，努力达到目的。yòng jǐn quán bù lì liàng qù zuò mǒu shì nǔ lì dá dào mù dì

竭 (jié, "exhaust") + 力 (lì, "strength") presents determined action as strength used without reserve.

In everyday conversation, this verb often sounds formal, so it fits reports, promises, and serious statements more naturally than casual chat.