used to say that something happens very quickly and when you are not expecting it 转眼之间,一下子
You’ll be home before you know it.
一眨眼工夫你就会到家了。
Examples from the Corpus
before you know it• Springbreak will be here before you know it.• You'll be fully recoveredbefore you know it.• It happens before you know it.• Take time with people, and you will see success in your business before you know it.• They claim that news is just around the corner, and that it will be on us before we know it.• One thing kept leading to another, and before I knew it a small industry had been set in motion.• You offer to iron his shirt and before you know it, he expects you to do all the housework.• He saves his money, before you know it he owns a car.• It seemed a long way away but before we knew it we were paying the last of the deposits.