过去并没有死去；它甚至还没有过去。
The past is not dead; it is not even past.
Sustainable development requires balancing economic benefits with environmental protection.
Science fiction is the literature of change.
I like to be challenged. I like to do things that people say I can't do.
The security dilemma is a fundamental feature of international politics, as states' efforts to increase their own security often decrease the security of others.