651.________ around the Water Cube,we were then taken to see the Bird’s Nest for the 2008 Olympic Games.
A.Having shown
B.To be shown
C.Having been shown
D.To show
652._______ that he was in great danger,Eric walked deeper into the forest.
A.Not realized
B.Not to realize
C.Not realizing
D.Not to have realized
651.答案是C;show与take之间有明显的时间先后关系，且主语与show构成逻辑上的动宾关系，故用现在分词完成时的被动形式。
652.答案是C;realize与主语构成主动关系，且realize和walk两动作几乎同时发生。
