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1.The city has installed sanitary sewer manholes in all residential areas to improve the environment.
该市已在所有居民区安装了卫生下水道井盖，以改善环境。
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2. The construction of the sanitation system will greatly enhance the sanitary sewer manholes' ability to handle wastewater.
卫生系统的建设将大大增强卫生下水道井盖处理废水的能力。
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3. The sanitary sewer manholes are designed to prevent sewage from entering the streets and polluting the environment.
卫生下水道井盖的设计旨在防止污水进入街道，污染环境。