Inhale for three seconds, then smoothly exhale for three more.

吸气三秒钟，然后缓缓地呼气，呼气要超过三秒钟。

youdao

It says that goldfish can only remember things for three seconds.

书上写着金鱼的记忆力只有三秒钟。

youdao

Three-second violation: an offensive player may not stand in the lane for three seconds.

三秒违例(three - second violation)：进攻球员在通道内不允许停留三秒。

youdao

"He was telling me I need to finish second, and he was also telling me 'Don't step on the line,' and he was also telling me, 'Just try to stay close.' They shot the gun and I saw him for about maybe two or three seconds.

VOA: standard.2009.08.21

Do not think of a pink elephant for the next three seconds ? and I am sure no one thought of a pink elephant right?

在接下来的十秒钟里不要想粉色大象,我肯定没有人想一头粉色大象，是吗？

哈佛公开课 - 幸福课课程节选

During the flight, father-of-two Mr Connery dropped for three seconds before his suit "started to fly".

BBC: Gary Connery in world's first skydive without parachute

Under Ofcom regulations, broadcasters must inform viewers by displaying the letter 'P' for three seconds at the start and end of a programme that contains product placement.

BBC: Product placement ban on British TV lifted

Maybe I'd like a billion for three seconds, or 10 billion, just the way I might need a million computers in the cloud for two seconds and can access them through Google.

WSJ: The Weekend Interview: Will Google's Ray Kurzweil Live Forever?