YOU SAID:

Why does a cat purr when it eats?

INTO JAPANESE

それを食べるとき猫がゴロゴロするはなぜですか。

BACK INTO ENGLISH

The cat to purr when you eat it, or why.

INTO JAPANESE

理由や、それを食べるときにゴロゴロする猫。

BACK INTO ENGLISH

Or why a cat to purr when you eat it.