Backdoor
a. 秘密的
✅ 同义词
🗣️ 情景例句
Hi, Peter.
彼得，你好。
All rivers run into the sea.
百川入海。
At night, when you really wish to go to sleep, you rarely manage to do so.
到了夜晚，你真想睡了，却很难入睡。