Bat flies at night and can also catch moths and mosquitoes; and no matter how it flies, it has never collided with anything. Even a very thin wire can be dexterous. avoid. Could it be that its eyes are so sharp that it can see everything clearly in the dark night? In order to clarify this problem, scientists conducted an experiment more than 100 years ago. There were many ropes stretched across a room, and many bells were tied to the ropes. They blindfolded the bat and let it fly around the house. The bat flew for several hours without ringing any bells. It did not touch any of the many ropes. The scientists conducted two more experiments: one plugged the bat's ears, and the other sealed the bat's mouth and let it fly in the house. The bats were scurrying about like headless flies, and the bells hanging on the ropes kept ringing. Three different experiments have proven that bats fly at night not by their eyes, but by the cooperation of their mouths and ears to find their way. After repeated research, scientists finally revealed the secret of why bats can fly at night. As it flew, it made a sound from its mouth. This sound is called ultrasonic sound, which is inaudible to human ears, but can be heard by bat ears. Ultrasonic waves push forward like waves, and when they encounter obstacles, they are reflected back and reach the bat's ears, whereupon the bat immediately changes its flight direction.