求分析这篇文章的逻辑结构（行文思路）！

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读了好几遍了都没明白。。各段之间到底什么关系。。。

As with impact structures, studies of African meteorites, as well as expeditions dedicated to the search for meteorites, have in the past generally been directed by non-African institutions. Obviously this has a lot to do with availability of funding for such work. It is, however, strongly felt that the widely noted lack of knowledge about the importance of the study of meteorites, of how to identify them, and of impact structures also contributes to this one-sided research situation.

Meteorites, especially the iron and stony-iron meteorites, can be recognized by their metallic or semi-metallic appearance, frequently grooved surface structure, and strong magnetism. It is important that, when such material is discovered, all information, for example about its position, orientation on the surface, time of fall, and any visual observations made or sound heard, be meticulously recorded.

Contamination from metal tools and chemical reagents must be avoided. That said, a small number of scientists, for example at the Universities of Cape Town, Cairo, and of the Witwatersrand in Johannesburg, have in the past actively studied meteorites. While these institutions display requisite expertise for the task, they tend to work in isolation.