water demand的用法和样例：
例句
- Knowledge of historic and present water demands is needed to provide a factual base for predicting future water demand.
应了解过去和当前的需水量，以便为估算未来的需水量提供实施依据。 - With the restriction of water demand and supply, the objective function optimal value was calculated by sequential quadratic programming.
以需水量和可供水量为约束条件，采用序列二次规划法求解函数最优值。
