If we can know their frequency we will monitor their talking.

如果们知道们的, 们就能监听们的谈话。

We have been monitoring the enemy's radio broadcasts to try to find out their secret plans.

"们一直在监听敌方的电台广播,设法查探们的秘密计划。"

This instrument monitors the patient's heartbeats.

这台仪器监听病人的心跳。