[填空题]
Eclipses happen on Earth because of q yof.e e tp;+klo,5.fy+--vxqfdl 2nan amazing coincidence. C(,g zmi pnc17balculate, using the information inside the Front Cover, the angular diameters (in r(pgzbmc 71, inadians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$