Mozambique, Angola and other countries are former colonies of Portugal, so the official language is Portuguese.
Congo, Congo and Central Africa were colonized by France and Belgium, so French is the official language.
The reason why the above languages were designated as official languages was also forced. Because there are great differences in indigenous languages in many parts of Africa, if the language of one tribe is rigidly stipulated as the official language, it will inevitably cause dissatisfaction among other tribes.
But in fact, in many places, the local languages are similar. For example, most of Africa is home to Bantu Nigro people, whose language belongs to Bantu family, and some words and grammar can be used together. For example, the prefix "Ki" or "chi" indicates a language, followed by a tribal name. Ki-congo refers to Congolese, and chi-nyanja refers to the language of Nyang people in Zambia. These languages are different from the surrounding tribal languages, but there are similarities.