The Liskov Substitution Principle (LSP) is one of the basic principles of object-oriented design. The Richter substitution principle says that wherever a base class can appear, subclasses can certainly appear. LSP is the cornerstone of inheritance reuse. Only when derivative classes can replace base classes and the functions of software units are not affected can base classes be truly reused, and derivative classes can also add new behaviors to base classes. The Richter substitution principle is a supplement to the "open-close" principle. The key step to realize the "open-close" principle is abstraction. The inheritance relationship between the base class and the subclass is the concrete realization of abstraction, so the Richter substitution principle is the specification of the concrete steps to realize abstraction. --From Baidu
As for why, look at the following development cases.
谁敢不让咱孙女吃螃蟹，爷爷把他给吃了。
//Technical interview
It can be said that all kinds of strange and strange types are included.
五名精英猎人出钱在荒岛上追捕一名男子，却发现自己成了猎物。
但是，我错了，我太天真了，不该把一切事物都想得很美好。
3. Physical period: Uniform circular motion is a kind of periodic motion. The so-called periodicity refers to the fact that after a certain period of time, the moving object repeats back to its original position, and the instantaneous speed repeats back to its original size and direction. The time it takes for an object to move in a uniform circle is called a period. The period is expressed by the symbol T, and the period is also a physical quantity describing the speed of uniform circular motion. The long period indicates the slow motion of the object, while the short period indicates the fast motion of the object.
曹承佑饰演天才工程师主角，人称国民英雄，由于无法置信哥哥的死亡而开始调查世界中隐藏身份的存在而陷入危险。朴信惠饰演在另一个军阀割据的世界中的最强战士，为保护主角不畏艰难的来到另一世界。
For example, from November 1, 2015 in Hebei, the health fee for female employees will be adjusted from 4 to 6 yuan per person per month or the corresponding health supplies will be increased to 30 yuan per person per month or the corresponding health supplies.
该剧通过四种孩妈的“奴生活”直击“由孩子引发的一系列”都市家庭、夫妻情感等现实话题，揭示了浮躁社会中，为了孩子的未来，不惜拼上一切的父母苦涩、无奈、愤怒、悲愤的现状，发人深思，成为荧屏上首部“反奴剧”。
(two) to stop practicing for more than one year;
1895年，一对男女神童降世。两个孩子在同一时辰出生在上海西城某家医院，他们的母亲在产后离开了人间。皇太后因得知天命神童能解救天下贫苦的百姓，便下令在他们出世后立即除掉。尚蔲为了保护天命神童的安全，安排法国人马丁将他们带去法国，并将他们抚养长大。皇太后又派忠臣普顿前往法国追杀这对神童，因这对神童相握手时，会产生无穷的魔力，双方于是展开了激烈的斗争，天命神童战胜了邪恶势力并最终返回到中国；通过更换父亲的碑文，救活了他们自己的父亲。随后天命神童便丧失了魔力成为了两名普通的孩子，并开始了新的生活。
夏侯婴道：宋义也不是省油的灯，这下子有好戏看了。
绿菠兴奋地告诉大家道：我们和三姐姐都说好了，等二哥三哥考完了再过中秋，好好庆贺。
Dark mode. The color information of each channel and the mixed pixel color are examined, and the darker one is selected as the mixed result. The brighter pixels will be replaced by the darker pixels, while the darker pixels will not change.
田夫子见了忍不住瞪了他一眼。
