Definition of Basal Drag?

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

Japan is a group of four islands off the coast of asia. what effect do you think has had on the lives of the japanese?

Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.