Which ones are true about six criteria for evaluating how communicative classroom activities are? ( )
选项：

A:The activity should involves the students in performing a real communicative purpose rather than just practicing language for its own sake.
B:When students are doing the activity. They must focus on the form, not on the meaning.
C:The activity must be designed to be done by students working by themselves rather than with the teacher.
D:The activity should be designed to control what language the students should use.