1. In places, the water table is declining at a rate of a meter a year, necessitating the periodic deepening of wells and the use of ever-more-powerful pumps. 在一些地方，水位正以每年一米的速度下降，需要定期加深井并使用更强大的水泵。
2. The filters become dirty after they are used for a long time necessitating replacement. 过滤器成为肮脏后，他们用相当长的时间需要更换。
3. Additionally, rising number of power plants is necessitating the need for pet coke for use as a fuel. 再加上发电厂数的增加，需要作为燃料的石油焦。
4. The conversion-per-pass is generally low, thus necessitating gas recycle to increase overall product yield. 其单程转化率一般是低的，因此有必要使气体循环以提高总的产品收率。
5. It described a simple session EJB method that updates both JDBC and JMS data, necessitating an XA transaction. 它描述了通过一个可以更新jdbc和JMS数据的简单会话ejb来实现xa事务。
