In what situation will students be sent to the principal’s office? A. When they don’t finish their homework. B. When they speak out of turn.(抢着发言) C. When they are late for class.
【单选题】A satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. If g m is the acceleration due to gravity at the surface of Mars, what is the acceleration due to gravit...