The past is always tense, the future perfect.

要解决问题，你必须愿意以不同的方式思考。

All men have the stars, but they are not the same things for different people. For some, who are travelers, the stars are guides. For others they are no more than little lights in the sky. For others, who are scholars, they are problems. For my businessman they were wealth.

历史给我们的教训是，人们从来都不知道汲取历史的教训。