所以老外說「I'm in the black」
意思是「我有閒錢了」
例：
This year our business is in the black.
今年我們的生意有盈餘。
而穿著黑色衣服用in black
例：
He was dressed in black.
他穿著黑色衣服。
和in the black意思相反
例：
The company was already in the red to the extent of more than three million pounds.
這家公司已經出現了超過300萬英鎊的負債。
身處黑暗裡，對周圍環境是模糊不清的
in the dark表示：蒙在鼓裡，渾然不知
例：
I managed to keep my parents in the dark about this.
我設法讓父母對這件事一無所知。
如果想表達「在黑暗裡」可以用in the darkness
例：
In the darkness I bumped into a chair.
在黑暗中我撞到了一把椅子。
in the bag除了「在袋子裡」
還可以引申用來表達「十拿九穩；已是囊中之物」
例：
Once we'd scored the third goal, the game was pretty much in the bag.
我們進了第三個球後，比賽取勝已是十拿九穩了。