The designer himself is not sure whether this software is appropriate（）children under 12 years old.

A．online courses are becoming more important than traditional courses
B．online courses were different from traditional courses
C．online courses are becoming more popular in college education
D．online courses are actually not different from traditional courses

A．Employer and employee.
B．Teacher and student.
C．Seller and customer.
D．Interviewer and interviewe