求翻译：20世纪80年代和90年代将校车的制造商整合，减少的校车的制造厂商保证了质量，并且产品随之也开始有了创新。并且将校车分类型，共分成A型、B型、C型、D型，下面就是校车分级介绍。是什么意思？

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In the 1980s and 1990s the school bus manufacturers will be integrated to reduce the school bus manufacturers guarantee the quality of products, and have also started innovative. School bus types, and will be divided into sub-type, B A C-type, type, the following is in transition, D bussing classifi

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In the 1980 of the 20th century and 90 are verified vehicle manufacturers integrate, reducing school bus manufacturers ensure the quality, and product, with that start with innovation. And are verified vehicle types, type total into type a, type b, c, d, is the school bus classification described be