Mary is my good friend. She's good-looking but she's quiet.
A：a bit of
B：a lot of
C：a little bit
D：a few
起重机将物体由静止举高h时，物体的速度为v，下列各种说法中正确的是(不计空气阻力)( )
若函数fx=x2+ax+b有两个零点cosα,cosβ，其中α,β∈0,π，那么在f-1,f1两个函数值中 ( )
