system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can people understand languages, but not speak them ?
gpt
Because recognition of language is a lot easier than generation of language. If you've ever studied a language, you've probably noticed that you have more trouble thinking of the foreign word when presented with your native word than you do if you're presented with a the foreign word and have to come up with your native word for it. Then consider grammar and sentence construction. Even if you don't know how to construct a sentence in the language, if you understand the words you can probably get the gist of what they're saying just because you recognize the verb and nouns that are there. But if you had to create a well-formed sentence on your own, you'd have no idea how to do it.