Farmers are extremely busy during the harvest.

农民在收获季节里十分忙碌。

《牛津词典》

I'm extremely busy.

我非常忙。

youdao

Well, I know you're all extremely busy, so why don't we get started?

我知道你们都特别忙，那就赶紧开始吧。

youdao

So in 2009, movies, visual effects industry was very slow, but 2010, it's extremely busy.

所以，在2009年，电影、视觉特效行业发展很慢，但是在2010年，这些行业发展得蒸蒸日上。

经济危机和电影市场 - SpeakingMax英语口语达人

He said life in space was extremely busy, with no spare time to be idle.

BBC: Chris Hadfield: 'Space was too good not to share it'

"We were extremely busy and still are, although there were quieter periods last year, " he said.

BBC: Tourism dip a blip, says hotelier

The fires are the latest in an extremely busy period for firefighters across south, mid and west Wales.

BBC: Grass fire threat to overhead wires near Pontycymer