Forest entomologists have concentrated on ecological problems. 森林昆蟲學家所重視的是生態問題。
Sewage itself is another major contaminant of water that can cause ecological problems and such human diseases as cholera and dysentery. 污水是引起水體污染的另一個重要因素，它會導致一些生態問題，使人引發霍亂和瘧疾。
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