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Program testing can be used to show the presence of bugs, but never to show their absence!

The most important political development of the last half century has been the spread of liberal democracy around the world.

The theory of economic development is the study of how the economic system generates the forces which incessantly transform it.

美好生活是一個過程，而不是一種狀態(tài)。它是一個方向，而不是一個目的地。