Life is an endless cycle of repeat and renewal, deducting or adding the parts that are mature and in need.
生活就是重复与更新的不断循环，减去到期的部分，增加需要的部分。
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The fifth chapter puts forword renewal strategies of old residential areas with the theoretic instructions of Healthy City, which includes two parts of spacial planning and neighbourhood planning.
Currently, machine parts parametrized CAD systems are available in the market. Some of them may be powerful but they are enormous in volume, high in price, and awaiting renewal of computer technique.