The word you're looking for is waning. When the moon's illumination is increasing, it is waxing.
I would say that the US and the Soviet Union at the end of WWII withdrew their troops as soon as a demilitarized zone was created. Also, I am sure they would require a peace treaty to be signed with Germany before withdrawing troops.
Answer: Most submarines use sonar as a navigation aid. How would sonar enable an underwater vessel to move through the ocean depths? It would enable an underwater vessel to move through the ocean depths because it would tell the navigator how far away they are from the bottom, and if they are too close or too far.
Oceanographers study the ocean through sonar and submersibles. Oceanographers use sound waves(sonar) to find the location of objects or to communicate. The sound waves travel to the ocean floor then back, and oceanographers count how long it takes to find how deep the ocean is at that location. Oceanographers use that to make maps and profiles of the ocean floor. Oceanographers use submersibles to study the ocean depths. Submersibles help oceanographers make discoveries about the deep ocean.
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