【单选题】According to gyroscopic precession, if the rotor disc wants to tilt forward, which direction the pitch angle has to increase? Assuming the main rotor rotates counterclockwise,and 3-o'clock is on the r...
【简答题】A.The helicopter can fly forwards, backwards, up, down, and sideways. B.The helicopter can hover in the air. C.The helicopter can land and take off from a flat roof. D.The helicopter has a single-blad...
【简答题】Hardly ________ the helicopter ________ when the waiting crowd ran toward it. A) has ... landed B) had ... landed C) would ... land D) was ... landing
【单选题】听力原文:(A) The helicopter is on the ground. (B) There is a column-like tower in the picture. (C) The plane wants to rescue the man on the tower. (D) The helicopter has some engine problems.