What are the many islands people also called

What does the word submerged mean in the following sentence? after it rained for three days in a row, the streets were completely submerged.

Scientist believe that earths core is around 6000°c where does this heat come from

Trade routes emerged along which coast when arab and indian traders from around the indian ocean mixed with the bantu people from africa's interior? a. swahili coast b. guinea coast c. drakensberg coast d. namib coast