How / why / by what means (何以)

Structure 何以 + verb（asking means or reason）

何以 (héyǐ) is a Classical Chinese interrogative still alive in cultivated register: placed before the verb, it asks about MEANS («by what?, how?») or REASON («why?, how come…?»). It corresponds to modern 怎么 / 为什么 / 用什么, but sounds literary and solemn. It shows up both in set phrases (何以见得 «what makes you think so?», 何以解忧 «with what shall I drown my sorrow?») and, productively, in rhetorical questions in essays. 何 keeps its literary sense of «what/how» and 以 (yǐ) that of «with/by means of».

Examples

你nǐ何hé以yǐ见jiàn得de他tā在zài说shuō谎huǎng？
What makes you so sure he's lying?
何hé以yǐ解jiě忧yōu？唯wéi有yǒu杜dù康kāng。
With what shall I drown my sorrow? Only with wine.
他tā何hé以yǐ如rú此cǐ自zì信xìn，我wǒ不bù得dé而ér知zhī。
How he can be so self-assured is beyond me.
何hé以yǐ报bào答dá您nín的de恩ēn情qíng？
How could I ever repay your kindness?

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.