The old man wondered________．A.whether the American pilot had seen UFOsB.whether had the American pilot seen UFOsC.how had the American pilot seen UFOsD.that the American pilot had seen UFOs
网友回答
A解析分析：B、C的词序错了。A、D的时态都是过去完成时，正确，区别是引出词的不同。主句的谓语动词是wondered(想知道)，宾语从句应该带有“不确定性”，whether(是否)有不确定性(直接引语是一般疑问句，当然有不确定性)，而that引出的宾语从句来源于陈述句，没有不确定性。