Every year, we plant many trees on _______ side of the road to make our city more beautiful.
A:both
B:all
C:each
D:neither
数列3,3,15,21,33,…,则9是这个数列的第( )
“我在东方看到了喷油的泉,可以燃烧的石头,用轻巧的纸张做的货币……”“君主有一大宫,其顶皆用精金为之……宫廷房屋地铺金砖,以代石板”以上这些文字出自( )