The radial component of velocity for a particle moving in a circular path is____（）
A non-zero constant
B. Radius itself
C. Variable
D. Zero
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Which of the following is a scalar quantity（）
A. speed
B. time
C. length
D. instantaneous acceleration
E. instantaneous velocity
F. average velocity
G. average acceleration
H. magnitude of position vector
I. none of the above
In the processing of pasteurized milk, the minimum processing is to destroy（）
A. Clostridium botulinum
B. pathogens such as salmonella, mycobacterium tuberculosis
C. enzymes
D. molds
Which statement about values is incorrect（）
A. Values are social principles, goals, or standards accepted by persons in a culture
B. Values are learned by contacts with family members, teachers, and religious leaders
C. Values will be influenced by what is seen on television or read in newspapers
D. People in various cultures have basically similar values
同时设置了enable secret和enable password两种特权密码，（）密码有效
A. enable secret
B. enable password
C. 两种
D. 没有
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