People believe that we ______a special ability to learn language and that our brain _____ itself to the language we hear.

A．are prepared for；adjusts

B．are equipped for；adapts

C．are armed by；fits

D．are equipped with；adjusts

如右图所示，一个木块放在固定的粗糙斜面上，今对木块施一个既与斜面底边平行又与斜面平行的推力F，木块处于静止状态，如将力F撤消，则木块(　　)

A．仍保持静止

B．将沿斜面下滑

C．受到的摩擦力大小不变

D．受到的摩擦力方向不变