1. But even the mosquito has been subdued by attention to drainage and by chemical sprays.
    然而即使蚊子，也由于我们注意清理污水和喷洒化学药品就被制服了。

2. Workmen put in a proper drainage system and supplied pure drinking water.
    工人安装了合适的排水装置，提供纯净的饮用水。

3. The town´s drainage is very efficient.
    这城市的排水系统很好。

4. The city was even equipped with a drainage system, for a great many clay pipes were found beneath the narrow streets.
    城里甚至还敷设了排水系统，因为在狭窄的街道底下发现了许许多多陶土制作的排水管道。