This is _ class.So the teacher doesn't know all of his students.

问题描述:

This is _ class.So the teacher doesn't know all of his students.
A .their first B.a their first Ctheir the first D a first
选哪个,为什么

The teacher _____ a class is a class teacher.\r\nA.is in charge of B.in charge of C.in charge\r\n选项是B\r\nin charge of 是介词短语,做定语.in charge用作副词,做状语.