hundred, thousand, million, dozen, score,前面有具体数字或several修饰时，用单数形式。与of连接，用复数形式：hundreds of(数以百计)，thousands of(成千上万)，millions of(数以百万计), dozens of(几十)。

　　【例如】

　　The pupils in this school raised several hundred dollars for the hungry people in Africa.Millions of fans have been watching the football match recently.He made dozens of tests to prove that the new medicine was quite beneficial to the patients.