[填空题]
Eclipses happen on Earth because of an amazing/a2z zbla8tg 9+48g ctnxia7x coincidence. Calcut+5 ;1ufn/yw bhcwfid06/eb54 k3 ewmdwyi .qlate, using the information inside the Front Cover, the an /5b;dhi. fudywn 1ce5wemfktyi4/ 036qw wb +gular diameters (in radians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$