全速;全力以赴
as fast or as hard as possible
My car only does about 60 mph, even when it's going flat out. 我的车即使全速行驶，也只能跑到每小时60英里左右。
We've been working flat out to get this done. 为了完成这项工作，我们一直在全力以赴。
Oil refineries are currently running flat out to satisfy the demand.
They were galloping flat out along the beach.
She's been working flat out all summer and she really needs a break.
See also: flat adverb (COMPLETELY)