[填空题]
Eclipses happen on Earth because of afsfodq3 rpw (r3c.p-pi;t qh8 5*i6son amazing coincidence. Calculat:/uyz*bm5/ 8fl e3k-eu8j7mpfi.:mckt pr xde, using the information inside the Front Cover, tmk:ef3md lrxk f/t8p mpcb5z*7.: u-/yi8eju he angular diameters (in radians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$