Backdoor
a. 秘密的
✅ 同义词
🗣️ 情景例句
You must be very tired after the journey.
旅行之后，您一定累了吧！
Just a short line to say thanks.
只言片语聊表谢意。
Of course, Father Christmas isn't real.
当然，圣诞老人并不是真的。