to do or say something before someone so that you make their words or actions unnecessary or not effective

The minister held a press conference in order to pre-empt criticism in the newspapers. 部长召开了记者招待会，旨在先发制人，预先防备各报纸的指责批评。

You need to be prepared and preempt the impact of the change before it happens.

to replace one television programme with another, usually more important one

All the networks pre-empted their regular schedules to broadcast news of the hijacking. 所有的电视网都取消了安排好的节目，转而播放劫机的新闻。

For several days, this story preempted all others in the news schedules.