The four main parts are:
Heart
Blood vessels
Blood
Lymphatic system
Hope that helps <span>
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It is an indicator of poor air quality from air pollution. This pollution is most often ozone or particulates. Typically it indicates that the air is unhealthy for children, the elderly, and sensitive groups.
Answer:When one has a non-living specimen that is no thicker than a few micrometers.
Explanation:
