Unavailability
[计] 无效性, 不可用性
🗣️ 情景例句
Use a dictionary and grammar guide constantly.
经常使用字典和语法指南。
The more a man knows, the more he is inclined to be modest.
大智若愚。
I'm afraid I don't have it any more. I sold it last week.
我恐怕是没有了，上星期我把它卖掉了。