B. Online courses can be broken down into several categories. C. Students can be broken down into several categories. D. Teachers broke down into several online course categories. Question 20: A. In a classroom , the students to spend time with a real teacher. B. They students spending time in classroom with a real teacher. C. They also spend time in a classroom with a flesh-and-blood teacher Question 21: D. With whom they spend time time a flesh-and -blood teacher A. supplementing traditional instruction, online resources don t replace it. B instruction replaces online resources and don't supplement it. C. online resources neither replace nor supplement traditional instruction. D. online resources supplement traditional instruction but don't replace it. Question 22: A. less proficient students tend to run into trouble B. less students proficient tend to run into trouble C. running into trouble,less proficient students tend to be. D. less students proficiency tend to run across trouble.