[填空题]
Eclipses happen on Earth because of an a l.6x okk.t 1e,1ulywamazing coincidence. Calculate, usin:(bopt jt 42f: fph.oyg the information inside the Front Cover, the angula:h fjtt4oypp:(f.2bo r diameters (in radians) of the Sun and the Moon, as seen on Earth. Sun = $rad$ Moon = $rad$