Nowadays _____ of business letters are written in English．

A．two third                B．two thirds               C．two three                D．second three

--What class are you in．Jim?

--I am in Class ________．And it is on the ________ floor．

A．Three；second          B．Third；second        C．Three；two

There is a big class and                       of the students are boys．

A．two third        B．second three        C．two thirds         D．two three