How did airplane use change as World War I progressed? Military forces became dependent exclusively on airplanes for fighting battles. Airplanes became involved in active battle. Fewer civilians took airplanes because of German threats. Airplane use declined, as there were insufficient materials to build new planes.

Layer r contains a well-known index fossil that is 100 million years old. based on this information and the principle of superposition, a. layers t and m are older than 100 million years, and layers x and g are younger than 100 million years. b. layers t, m, x, and g are all older than 100 million years. c. layers t and m are younger than 100 million years, and layers x and g are older than 100 million years.