阅读下面材料，从每题所给的A、B、C和D四个选项中选出最佳选项。How do blind people get around safely? Some people use special guide dogs. A well-trained dog knows how to help its owner cross busy streets and get from place to place. Some people use long white canes（手杖）to help them get around.
Guide dogs and canes are helpful, but there must be a better way for blind people to get around. A scientist in England thought so. His name is Waters and he studies bats（蝙蝠）. He knows that bats are able to fly in the dark. Besides, he knows that bats go by using sound to "see". Dr. Waters wondered if people could do something similar.
Bats make sounds as they fly. These sounds travel in waves（波）in the air. When the waves hit an object such as a tree or house, they bounce back（反射回来）. The waves travel back to the bat's ears. A bat learns the location and shape of objects around it.
Dr. Waters talked to other scientists, including Withington from America and Hoyle from Germany. They worked together and invented a new kind of cane. They called it a "bat cane" because their idea started with bats. The new cane has a computer in the handle（手柄）. ▲ The sound waves hit objects and echoes（回声）back. This causes the handle to make sounds, which humans can hear.
With a little training, a person using the cane can easily tell where objects are and can "see" with sound!
