There are about six        students in our grade and             of them are girls．

A．hundreds，two-thirds                       B．hundred，two-third

C．hundred，two thirds                           D．hundreds，two third

--There are 50 students in our class, and 20 of them are girls.

--That is to say(也就是说), 　 of the students are boys.

A.three fourths　 B. two thirds　 C. three fifths