in one meaning in English
成为一体
合为一体
合在一起
在某人裤子后口袋里（是某人的囊中之物）
Examples
- You can read this book in one sitting .
你可以坐着一气把这本书读完。 - He tends not to stay in one place for very long .
他在哪儿都呆不长。 - These pictures are unusual in one respect .
这几张照片具有独到之处。 - We flew from london to bombay in one hop .
我们从伦敦直接飞到孟买。 - They were lucky to get back in one piece .
他们安全返回，十分幸运。