Longitude is the measurement east or west of the prime meridian. (Imaginary lines that run around the Earth vertically. up/down.)
These subs are useful in studying the ocean floor, where it is so deep that divers would be crushed by the water pressure. For example, research submersibles are used to study shipwrecks like the RMS Titanic.
The president s of the united states
Acid rain threatens the world's food supply.
Acid rain is a global issue.
The troposphere because it has half of all air in the Atmosphere
