1. 他有两个儿子，一个是教师，另一个是医生。
    He has two sons, __________ is a teacher, __________ __________ is a doctor.
2. 操场上有许多男孩，一些在踢足球，另一些在打篮球。
    There are many boys on the playground. __________ are playing football, __________ are playing
    basketball.