空气质量对人类健康的重要性不言而喻。

Kōngqì zhìliàng duì rénlèi jiànkāng de zhòngyàoxìng bùyán'éryù.

The importance of air quality to human health is obvious.

努力对成功的重要性是不言而喻的。

Nǔlì duì chénggōng de zhòngyàoxìng shì bùyán'éryù de.

The importance of hard work for success is self-evident.

在信息时代，掌握外语的重要性早已是不言而喻的事实。

Zài xìnxī shídài, zhǎngwò wàiyǔ de zhòngyàoxìng zǎoyǐ shì bùyán'éryù de shìshí.

In the information age, the importance of mastering foreign languages is already a self-evident fact.