21．(2012·广西老牌高中一调)________successful docking of Shenzhou VIII with TiangongI means that China has managed to take________first important step to establish its own space station.
A./; / B．A; a
C．The, a D.The; the
答案：D 考查冠词。句意：神舟八号和天宫一号的成功对接意味着中国已经迈出了建立自己空间站重要的第一步。第一空动名词docking后有of短语限定，为特指，故应该用定冠词the；第二空特指第一步，为序数词，故应该用定冠词the。由此可知选D。
