20. （2011•上海卷• T33）At one point I made up my mind to talk to Uncle Sam. Then I changed my mind ______ that he could do nothing to help.
A. to realize B. realized C. realizing D. being realized
【解析】选C。考查非谓语动词。句意为：我一度下定决心和山姆叔叔交谈。然后，当意识到他不能帮忙时，我改变了主意。I 与realize之间是主动关系，因此要用realizing形式表示主动关系，故选C。
