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 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。
3
It described a simple session EJB method that updates both JDBC and JMS data, necessitating an XA transaction.