未知题型 Tom Murphy and his colleagues fire laser beams at reflectors on the moon with the aim toA．measure the distance between the moon and the Earth.B．calculate the speed of light.C．check how long it takes light to cross it.D．prove the equivalence principle more accurately.

未知题型 The study by the American Management Association showed thatA．information on a public computer is not confidential.B．people should try to prevent themselves from being spied.C．using computers at work might pose a threat to privacy.D．employees should stop their electronic behavior. unrelated to work.

未知题型 From the second paragraph, we can learn that CremonaA．has more instrument workers than any other city.B．had many carpenters to make violins in the past.C．declined because of its carpenters' poor handcrafts.D．once was the capital of hand-crafted instruments.