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1·Insecticide resistance genes are useful when there's insecticide about, but not when there isn't: then, they can be detrimental.

抗药性在有杀虫剂的地方有用，但是在没有杀虫剂的地方就没什么用了：有时甚至是有害的。

2·Children have weak resistance in defending this detrimental influence.

孩子们在捍卫这一不利影响的抵抗力弱。

3·Sulfur is also detrimental to welding performance, reducing corrosion resistance.

硫对焊接性能也不利，降低耐腐蚀性。