[填空题]
Eclipses happen on Earth because of a4twcv:zz)2r y kh*;x pn amazing coincidence. Calculate, usinc 9qsajbrom1 ityf7g;gy1*n+3,g5 hsg the information inside the Front Cover, the angular diameters (in radians) of the Sun and the Moon, as s91 g mig g, cj13sq;tyy5sb *+no7afhreen on Earth. Sun = $rad$ Moon = $rad$