问题详情

Which of the following is NOT true about the ultrasonic torch？
A．It enables the blind to live a more normal life.
B．It is mainly used to scan the area in front of the operator for obstacles.
C．Fast succession of bleeps indicates that the obstacle is near.
D．Its sound can warn other people of the blind man’s approach.请帮忙给出正确答案和分析，谢谢！