1.We were going to have a surprise birthday for dad, but my silly brother let the cat out of the bag the day before.
2.In English, when we say ‘you mustn’t let the cat out of the bag’, it means that something is a secret and that you mustn’t tell anyone.
3.If you let the cat out of the bag, it means that you reveal a secret.
译文：
1. 我们准备给爸爸一个生日惊喜，可是我那愚蠢的弟弟在前一天就把秘密说了出去。
2. 在英语，当我们说’you mustn’t let the cat out of the bag’，意思是有一个秘密，你不可以告诉任何人。
3. 如果你 ‘let the cat out of the bag’，就是说你已经泄了密。
let the cat out of the bag = 原意是‘把猫从口袋里放了出来’，把秘密说了出去，泄密了
口语练习：
We are going to give XiaoQiang a surprise birthday, please don’t let the cat out of the bag.
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