[填空题]
Eclipses happen on Earth b2yd2 z,x; 0krm9aww : snjq4eqecause of an amazing coincidence. Calculayvub)u *w-4jmm tu2w1 te, using the information inside the Front Cover, the angular diameters (in radians) of the Sun and the Moon, m u-)ym*utb v1w24uwj as seen on Earth. Sun = $rad$ Moon = $rad$