单项选择题
A．measures the movements of a spaceship by means of light beam B．makes use of microwaves C．makes use of sound waves D．Both A and B
A．most people on the sidewalk were on the same side as himself B．no one suddenly turned into a doorway C．a man was looking into the windows of a store D．no one wiped his face with a handkerchief
A．he didn’t live very long with them B．the family was extremely large C．he was too young when he lived with them D．he was fully occupied with observing natur