【简答题】Why does the author say that European society, at least in the Nordic countries—is 'far less stable than America's' ? (Para. 3)
【单选题】自发性蛛网膜下隙出血最常见的病因是( )。
【简答题】Why is there hardly any difference between the price of European allowances to be delivered in 2008 and 2009 on the futures market?
【简答题】Why will NASA and the European Space Agency combine their efforts to explore Mars in the future?