请看以下标志

（1）你知道上面这些标志分别代表着什么吗？

a是                                                                                                                                             标志。

b是                                                                                                                                             标志。

c是                                                                                                                                             标志。

d是                                                                                                                                             标志。

（2）为什么要成立这些组织、设立这些标志？

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在面向对象的模型中，最基本的概念是对象和 。