We can surely overcome these difficulties as long as we are________united.
A:close
B:closely
C:closed
D:closing
若一个正多边形的一个外角是40°,则这个正多边形的边数是( )
有观点指出.西周的分封制实质上是一种比较原始的部落殖民政策,即用本部落联盟的贵族去统治被征服的其他部落。这一观点可表明分封制( )