【释义】若不是在正午半夜的时候,连太阳和月亮都看不见。描绘了三峡峡谷幽深、遮天蔽日的景象。
"When you are writing, you are trying to find out something which you don't know."
反馈是一个强大的概念,在自然系统和技术系统中被广泛使用。