01 between you and me
你我之間 ×
就我倆知道(保密) √
It's between you and me, don't tell anyone else.
這事就你我知道,別告訴其他人。
02 between them
在他們之間 ×
一起 √
Between them, they saved enough money to buy a car.
他們一起存錢買了一輛車。
03 in-between
中級的√
He's at the in-between stage, neither a child nor an adult.
他處於中級階段,既不是孩子,也不是成人。