The government tests fruits and vegetables at wholesale markets for agricultural chemical residue to protect the health of the public, but farmers themselves know best whether or not their crops have too much, and testing the products after they have arrived at the market isn't as nearly effective as beginning at the source.
像政府為保護大眾健康，在各批發市場檢測農藥殘留量，但農產品有沒有過多農藥殘留，其實農民自己最清楚，等產品到了市場再測試，效果自然不如由源頭做起。