[填空题]
A science-fiction tale describes an artiwk6m.oa jzu97 ficial "planet",42 l eiih6.z2c:j b.v;urok(c ivgpl in the form of a band completely encircling a sun (Fig. 5-40). The inhabitants live on the li( ;b ,2i vlpjo6ki.zrhv:cg u.ec42inside surface (where it is always noon). Imagine that this sun is exactly like our own, that the distance to the band is the same as the Earth-Sun distance (to make the climate temperate), and that the ring rotates quickly enough to produce an apparent gravity of g as on Earth. What will be the period of revolution, this planet's year, in Earth days?
