Being often used as pain-killer can give rise to the__________belief that cocaine is not an

addictive drug.       [ ]

A. stupid                              

B. mistaken      

C. improper                            

D. unsuitable

内燃机油酸值大于（）时，必须重新更换新油。

A.1.0mgKOH/g

B.2.0mgKOH/g

C.5.0mgKOH/g

D.1.1mgKOH/g