国家是理性的行为者，他们总是会按照自己的利益行事。
States are rational actors, and they will always act in their own self-interest.
The future of construction lies in materials that are both durable and environmentally friendly.
刻苦读书，即使功名未就，但使人品高雅，气度不凡；道德高尚，但不希图报答，时时恬然自安，饱食酣眠。
婴儿的哭声与其听起来一样严重。