A、computer or virus
B、computer not virus
C、computer and virus
D、computer near virus
A、reflection of the source
B、summary of the source
C、adaptation of the source
D、assessment of the source
A、The subject of the survey
B、The mode of the survey
C、The time of the survey
D、The content of the survey
A、Independent variable
B、dependent variable
C、Irrelevant variable