租客報怨廚房有臭味，但找不到臭味源頭。誰有這方麵的經驗？

租客說廚房有臭味已經3個星期了，他找遍了廚房各個角落，沒發現異常。

For the last 3 weeks, we have stinking smell that is unbearable in the kitchen dining area.

We checked under the stove, fridge and everywhere if it was a dead mouse or something.

哪方麵的專業人士能解決這類的問題？還有哪些可能性？謝謝。