Although many Americans move a lot, they still________and understand each other's dialects.
A:recognize
B:resign
C:remember
D:request
一只20Ω的定值电阻与一个最大阻值为60Ω的滑动变阻器并联,当滑动变阻器的滑片在两端之间滑动时,总电阻的变化范围是( )