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．Put up your hands. B．Don't move or I'll shoot you. C．If you want to have lunch, you must listen to me. D．You go first slowly and we'll have lunch together.
A．Henry Ford always tried to avoid waste B．Henry Ford required total observation once the standards were established C．Henry Ford always encouraged his workers to make changes oft he products D．Henry Ford made his own designs of his cars