There were ________ flies everywhere in my house.
A.dozens ofB.three dozensC.four dozens ofD.seven dozen of在线课程A
本句的意思是：我房里有很多苍蝇到处乱飞．句中的dozen是一个常用词，其意思是：twelve十二．有具体数词修饰时，不变复数．
1) dozen用作定语，放在名词之前．
They sold three dozen copies of this magazine.
这种杂志他卖出去了三打(三十六本)．
2) dozen构成短语dozens of．此短语的意思是：“a large number of许多” ．其用法与“hundreds of数以百计”；“thousands of成千上万”；“millions of数以百万计”差不多．例如：
He planned to buy dozens of reference books.
他打算购买几十本参考书．