n.the shortest distance that permits radio signals (of a given frequency) to travel from the transmitter to the receiver by reflection from the ionosphere
N
the shortest distance between a transmitter and a receiver that will permit reception of radio waves of a specified frequency by one reflection from the ionosphere 发送器与接收器之间的最短距离
You see, I'm a long-distance runner, a marathoner, and those pinchable, inline controls meant I could skip songs without feeling around for a button or taking my eyes off the road.
Mr. Obama's decision to skip over Israel during previous trips frustrated Israeli officials and the public, who saw it as an effort to distance the U.S. from Israel for the sake of repairing ties with the Arab world.