A、By giving some advice. B、By offering online courses. C、By understanding the students’ need. D、By improving his own ability. C

　　Teenagers and pre-teenagers are accustomed to using computers. (20) If they have been trained by a living and breathing teacher to do research and writing online, they are more likely to become proficient learners in an online course. However, if they primarily use computers for social media, shopping and gaming, chances of them tuning out those online activities to concentrate in a new way all by themselves are limited at best. Struggling students have difficulty judging when they need more review, forming a question to express where they lost the meaning of the content, knowing how to study, and setting the time aside from their social lives to do so effectively. (21) Online courses demand more independent learning because it is up to the individual to use the course and its online resources to maximum benefit. Students who just click through may be partially aware of what they aren’t getting-but when they post a question on Monday morning, it will be up to them to log in again Tuesday and try to make sense of the answer. (22) But for a real teacher, he can read a student’s performance and see the patterns to determine what the student needs. The teacher must set the learning goals and the steps to get there for that student. Yes, some teachers don’t possess the skills to do it well. But the reality remains; An online teacher can’t do this until we design a course where a face on the screen looks at that student in real time and responds. Until computers have that capability, forget the budget benefits.
　　20. How can teenagers learn online courses proficiently according to the speaker?
　　21. Why do online courses demand more independent learning?
　　22. How can a real teacher help his students?