She tried extra hard.

她特别努力。

《牛津词典》

That makes it extra hard to learn and practice it.

这使得学习和练习英语变得特别困难。

youdao

You will either have more of the right kind of energy to help your focus, or you'll need to work extra hard just to keep awake.

那么你就需要食用更多的适当种类的能量来帮助你提升注意力，或者你需要额外的工作来保持你的清醒。

youdao

Pfizer can be expected to engage in a pitched marketing battle against any competition, perhaps arguing that lowering bad cholesterol with statins has extra, hard-to-measure benefits that doing so with Zetia does not.

FORBES: Merck And Schering's Big Day

So parents give their children an extra banana or hard-boiled egg.

ECONOMIST: Cubans stand by for a long, hot summer

Further, says Peabody, world steel production is up 8% this year, requiring an added 75 million tons of extra hard and hot-burning metallurgical coal.

FORBES: Peabody Earnings Up, Coal Supercycle Just Beginning