[填空题]
A science-fiction tale describes an artificial "planet" in the form of a 5 4snk-(jzl5jwous n 1x3bes-yv5at3 cv 3w1zband completely encircling a sun (Fig. 5-40). The inhabitants live on the inside 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 yea3 1sc3xyva5-w3 bv eztr, in Earth days?
