[填空题]
What is the linear sp(c76di4kyee) mk:m c;li7nr jeed of a pointsj ymn)b y9* gn k8oufig55t++ (a) on the equator, $m/s$ (b) on the Arctic Circle (latitude 66.5$^{\circ} $ N), $m/s$ (c) at a latitude of 45.0$^{\circ} $ N, due to the Earth’s rotation? $m/s$