在了解物理力、它们的规律及相互关系之后，接下来是它们起源的问题。
My words in her mind: cold polished stones sinking through a quagmire.
数字革命不仅是经济问题，更是文化和民主问题。
The most significant threat to liberal democracy comes from within, from the decay of institutions and the loss of trust in them.