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·We proceeded to make the world's most desultory small talk, interrupted by every new arrival, each one necessitating a fresh discussion about who was on and who wasn't.
我们接着进行了世界上最不连贯的闲聊，不停地被新进入的人打断，每一次都需要重新讨论谁加进来了而谁还没有。
3·The AD7763 is ideal for applications demanding high SNR without necessitating design of complex front end signal processing.
AD7763是要求高信噪比（SNR）且无需要采用复杂的前端信号处理设计应用的理想器件。