251.dispel the mist and explain many phenomena that we thought of as mysteries in the past

　　252.both the senior citizens and the youth

　　253.Only this way can the essence the of traditional culture be inherited as it should be.

　　254.Zoos provide recreation and refreshment for fatigued urban dwellers.

　　255.dreamlands for small children

　　256.dragon's descendants 龙的传人

　　257.add to their knowledge something they will never acquire in the classroom

　　258.research facilities

　　259.gradually rises to 10% at 8:00 and maintains the same for the next 2 hours

　　260.There is ... increase ... ,however, after that it drops.