送有实用价值的物品，成为人们送礼的原则。
Presenting practical item has become a common principle among people.
越靠近混乱的边缘进行开发的团队，越容易开发出具有竞争力和有实用价值的系统。
The closer the development team operates to the edge of chaos, the more competitive and useful the resulting system will be.
对读者来说，他应该知道绝对值不是绝对会出现的一些值，也不是某种有实用价值的函数。
A reader is expected to know that an absolute value is not about some value that happens to be absolute, nor is a function about anything functional.
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