[填空题]
What is the linear speed o/ dyr )a+/d nd03hts /lx7ocm;arz d;wf e+vju p4uu3l y2+ kle+a point (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? $m/s$