水中捞月 trying to fish the moon out of water
Explanation
这个成语比喻做一些根本不可能做到的事情，只能白费力气。它告诉我们，做事之前要先考虑现实情况，不要做无用功。
This idiom is used to describe the effort spent on something that is impossible to achieve. It reminds us to be realistic and avoid wasting time and energy on futile pursuits.
Origin Story
从前，在一个宁静的夜晚，一位老渔夫坐在河边垂钓。他望着天空中皎洁的月亮，突然心生奇想，想把月亮从水中捞上来。他拿起渔网，奋力向水中一捞，却只捞上来了一把清凉的河水。老渔夫失望地叹了一口气，心想：月亮是天上之物，怎么能捞得上来呢？这真是水中捞月，徒劳无功啊。
Once upon a time, an old fisherman sat by the river fishing on a quiet night. He looked up at the bright moon in the sky, and suddenly he had a crazy idea. He wanted to catch the moon from the water. He picked up his net and fished hard into the water, but he only caught a handful of cool river water. The fisherman sighed in disappointment, thinking: The moon is a celestial body, how can I catch it? This is like trying to fish the moon out of the water, in vain.
Usage
“水中捞月”通常用来形容那些不切实际的想法和行为，比喻做一些根本不可能做到的事情。
“Trying to fish the moon out of the water” is often used to describe unrealistic ideas and behaviors. It compares the attempt to achieve something impossible to the act of trying to catch the moon from the water.
Examples
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想要一夜暴富，就如同水中捞月，痴心妄想。
xiǎng yào yī yè bào fù, jiù rútóng shuǐ zhōng lāo yuè, chī xīn wàng xiǎng.
To want to become rich overnight is like trying to fish the moon out of water, a foolish dream.
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在缺乏准备的情况下，贸然行动，只能是水中捞月，徒劳无功。
zài quē fá zhǔn bèi de qíng kuàng xià, mào rán xíng dòng, zhǐ néng shì shuǐ zhōng lāo yuè, tú láo wú gōng。
Acting rashly without preparation can only be like trying to catch the moon in the water, in vain.