题干
. When the policeman stopped us, we all looked questioningly at him, ?
A：nervously and puzzled
B：nervous and puzzling
C：nervous and puzzled
D：nervously and puzzling
答案(点此获取答案解析）
C
，现在B上作用一水平推力F，恰好使AB一起在桌面上匀速运动，且AB保持相对静止，则A与桌面的动摩擦因数
的关系为（ ）