"back out" in Chinese (Simplified)
取消（承诺）食言
Definition
决定不做之前答应过的事，或从约定、承诺中退出。
Usage Notes (Chinese (Simplified))
属于非正式用语，表示有人在临时改变主意或毁约。常和 'back out of a deal'、'back out at the last minute' 连用。不是指身体后退，用'back away'才是实际移动。
Examples
He promised to help but then backed out.
他答应帮忙，但后来**反悔了**。
She tried to back out of the agreement.
她试图**退出**协议。
Don’t back out at the last minute.
不要在最后一刻**反悔**。
They said they’d join us, but they backed out without explaining why.
他们说会加入我们，但后来什么都没解释就**取消了承诺**。
When money got tight, he tried to back out of the deal.
资金紧张时，他想**退出**交易。
I knew he would back out if things got complicated.
我知道如果事情变复杂，他就会**食言**。