单选题：Operating systems can be basically classified as______.

Operating systems can be basically classified as______. @[D](1)
A. batch systems, time-sharing systems and multi-tasking systems
B. real-time systems, batch systems and time-sharing systems
C. single-user systems, multi-user systems and batch systems
D. real-time systems, time-sharing systems and multi-user systems




A.batch systems, time-sharing systems and multi-tasking systems
B.real-time systems, batch systems and time-sharing systems
C.single-user systems, multi-user systems and batch systems
D.real-time systems, time-sharing systems and multi-user systems


答案：D