So they do no harm to the commercial operation.

所以它们无损经济作物的生长

Frogs do not eat plants, so they do no harm in a garden.

青蛙不以植物为食, 不会破坏我们的花园。

Never hurt the poor frogs, for they do no harm but much good.

千万不要伤害可怜的青蛙, 因为它们对人类有百利而无一害。