At least 2.3 million people took some kind of online course in 2004, according to a recent survey by The Sloan Consortium, an online education group, and two-thirds of colleges offering "face-to-face" courses also offer online ones. But what were once two distinct types of classes are looking more and more alike—and often dipping into the same pool of students.At some schools, online courses—originally intended for nontraditional students living far from campus—have proved surprisingly popular with on-campus students. A recent study by South Dakota’s Board of Regents found 42 percent of the students enrolled in its distance-education courses weren’t so distant: they were located on campus at the university that was hosting the online course.Numbers vary depending on the policies of particular colleges, but other schools also have students mixing and matching online and "face-to-face" credits. Motives range from lifestyle to accommodating a job schedule to getting into high-demand courses.Washington State had about 325 on-campus undergraduates taking one or more distance courses last year. As many as 9,000 students took both distance and in-person classes at Arizona State last year. The study by South Dakota’s Board of Regents shows that（） A: online courses are available at any time B: online courses are well accepted by on-campus students C: online courses should gradually take place of traditional courses D: online courses can be more beneficial for college students