each of the following questions from 18 to 22. A single teacher can reach thousands of students in an online course, (18) __ This limitless reach also offers substantial benefits for school districts that need to save money, by re reducing the number of teachers. However, in high schools and colleges.there is mounting evidence that the growth of online education is hurting a critical group: the less proficient students who are precisely those most in need of skilled classroom teachers. (19) __ and some are more effective than others. In "blended"courses, for example, students don't do their work only online: (20) __ . Research suggests that students - at nearly all levels of achievement - do just as well in these blended cl classes as they do in traditional classrooms. In this model, (21) __ . In the fully online model, on the other hand, a student may never be in the same room with an instructor. This category is the main problem. It is where (22) __ . After all, taking ion. Yet, in high a class without a teacher requires high levels of self.motivation, self -regulation and o organization schools across the country, students who are struggling in traditional classrooms are increasingly steered into online courses. (Adapted from https ://www.nytimes.com/) Question 18: A. which opens up a world of knowledge to anyone with an internet connection B. that opens up a knowledge of world to anyone with an internet connection C. that is opened up a world of knowledge to anyone with an connection interne D. where opens to anyone with an internet connection for a world of knowledge. Question 19: A. Several categories can be broken up for online courses.