解释:在人活动范围内的水就污浊,在野外无人地方的水就清洁。同为一样的水,都是从天边开源,有的混浊有的清洁,这是它们所处环境使它们这样的。
可持续捕捞不是一种选择;如果我们想保护海洋生态系统,这是唯一的前进道路。
The goal of mathematics is to understand the structures that underlie the phenomena we observe.
A great novel is a conversation between the author and the reader across time and space.