One of the boys doing homework in the classroom.A. is; their B. are; his C. is; his

问题补充：

One of the boys doing homework in the classroom.

A. is; their B. are; his C. is; his

答案：

解析：本题的含义为其中有一个男孩正在教室里做他的作业，主语为单数第三人称，故本题用is，他的物主代词为his，故本题选C。