[填空题]
What is the linear s:bmu o 15g(ziap--*q; zne xqt8mo2ubpeed of a pjrm857yu zgi- pz s5zh/+xl c)oint (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? $m/s$