for his passport. "You been to France before, sir？" the customs officer asked . Mr Whiting admitted that he had been to France previously. "Then you should know enough to have passport ready." The American said, "The last time I was here, I didn't have to show .""Impossible. Americans always have to show passports on arrival in France！" The American gave the Frenchman long hard look. Then he quietly explained, "Well, when I came in 1944 to help this country, I couldn't find Frenchmen to show it to."

　　难项分析：

　　第三处：had→have　考查动词的时态。根据before可知此处应用现在完成时。表示"以前来过"。

　　第四处：joking→jokingly　考查副词。修饰动词应用该词的副词形式，故改为jokingly。

　　第九处：liberating→liberate　考查非谓语动词。"帮助做某事"为help (to) do sth.。