520　out of breath，in a/one breath，catch one's breath和under one's breath

① out of breath喘气；上气不接下气（breathless）。

He is out of breath. 他上气不接下气。

② in a/one breath齐声地，立刻，瞬间，一口气。

They screamed all in a breath. 他们齐声尖叫。

In a breath the street was empty. 转眼之间街上就空无一人了。

③ catch one's breath屏住呼吸，歇一口气。

The story is full of surprises which cause the reader to catch his breath. 这个故事充满了惊险恐怖，使读者紧张得透不过气来。

After running to the bus stop we sat down to catch our breath. 我们跑到汽车站后坐下来喘了口气。

④ under one's breath 低声地。

She uttered something under her breath when her boss criticized her. 老板批评她时，她低声说了些话。