Ifndef
如果未定义
🗣️ 情景例句
I want to be with Max as a full-time mother,
我又想和Max在一起， 做个全职的母亲
I ate cakes for dinner yesterday.
我昨天晚饭吃的是蛋糕。
We had lost the path and had no hope of finding it again.
我们找不到那条小路，而且也没有希望再找到它了。