building combined drain

例句：

1. 1. The city has implemented a new combined drain to improve water quality.
   该市实施了一个新的综合排水系统，以改善水质。
2. 2. The engineer designed the combined drain with meticulous attention to detail.
   工程师仔细设计了这个综合排水系统。
3. 3. The construction of the combined drain is expected to begin next month.
   预计下个月开始建设这个综合排水系统。