[填空题]
What is the linear s. bnjdris5 r)o.e lq::u )k7beqbdu ky*gsa 4o, (-ov5asgr /+peed of 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? $m/s$