to interrupt what someone is saying by saying something yourself

I was just talking to Jan, when Dave cut in (on us/our conversation). 我正在跟简说话，戴夫插了进来。

to make a sudden sideways movement in order to position your car in front of another car, not leaving a safe distance between the two vehicles

Did you see that white car cut in (on us/in front of us)? 你看到那辆白色汽车抢超我们的车了吗？

Compare: cut someone up

If a machine cuts in, it starts, usually automatically.

If the computer starts to overheat, the fan cuts in. 如果电脑开始过热，风扇就会自动启动。

to interrupt two people who are dancing in order to dance with one of them

She was dancing with Jack, when Tom suddenly cut in. 她正和杰克跳舞，这时汤姆挤进来抢舞。

to allow someone to take part in something, for example a game or business

Shall we cut you in (on the deal/game)? 要我们让你入伙（做生意/玩游戏）吗？