1. The old peasant has five sons , _____are college students .
A .four of them B . four of whom C .and four of whom D .neither of them
2. This dictionary ,a few pages _____ are missing ,is of no use .
A .among which B .of which C .in which D .which
3. China has thousands of islands ,______ Hainan Island is the largest .
A .of them B .among which C .one of which D .among them
