hear sb do sth表示“听到某人做了某事”,hear sb doing sth.表示“听到某人正在做某事”,一些感观动词如hear,see,feel,watch等后面既可以接宾语+do sth,也可接宾语+动词-ing形式构成复合宾语.根据情景及句意的需要...如改成Did you hear someone knocking at the door有錯嗎?印象中,發問動詞好像要用基本式...Did you hear someone knocking at the door是 可以的没这说法