adj.最高的,坦白的,直率的;
adv.以最高速,坦白地,直率地;
例句:
After running in the marathon, she was flat out for a week.
她参加马拉松比赛后一星期都疲惫不堪.
Tell me flat out what you think.
坦率地告诉我你的想法.
I was going flat out but I still could not catch him.
我开车飞速前进,但仍然赶不上他.