问题补充：
The number of the students in our grade about six , of them are girls.
A. are, hundreds, two- thirds
B. is, hundred, two- third
C. is, hundred, two thirds.
D. are, hundreds, two third
答案：
A. are, hundreds, two- thirds
B. is, hundred, two- third
(答案→)C. is, hundred, two thirds.
D. are, hundreds, two third
解析：the number of表示的意思是……的数量，主语为单数，故第一个空用is，分数的表示法为分子为基数词，而分母为序数词，分子大于一，分母需使用复数，故三分之二可以写成two thirds，故本题选C。
