Unobservable
a. 难以察觉的；注意不到的；不可见的
✅ 同义词
🗣️ 情景例句
OK. I'll be back in a few minutes.
好，过几分钟我就回来。
Quality matters more than quanity.
质量比数量重要。
They then knew that they had discovered the cause of the fire.
这时调查人员知道他们找到了发生火灾的原因了。