of the students in our class interested in micro blogs (微博) on the Internet.A. Two fifth

问题补充：

of the students in our class interested in micro blogs (微博) on the Internet.

A. Two fifths; is

B. Two fifths; are

C. Two five; is

D. Two-five; are

答案：

A. Two fifths; is

(答案→)B. Two fifths; are

C. Two five; is

D. Two-five; are

解析：分数在英语中通常是借助于基数词和序数词来共同表达的。其中基数词表示分子，序数词表示分母。分子超过1，分母要加s.分数修饰名词时，若该名词是不可数名词只能用单数；若是可数名词，用单数或复数均可。但是，若它们在句子中作主语，则谓语动词是用单数还是复数取决于名词，即与分数所修饰的名词保持一致。