农田的排水系统需要定期清理以防止积水。

The ___drainage system in the field needs regular cleaning to prevent waterlogging.

这块农田需要更好的排水系统以防止积水。

This farmland needs better ___drainage to prevent waterlogging.

长江流域是中国最重要的农业区之一。

The Yangtze River ___drainage is one of China's most important agricultural regions.