实现流体静压润滑的条件是运动副应具有______。Ⅰ.较高的加工精度和表面粗糙度;Ⅱ.合适的表面硬度;Ⅲ.合适的配合间隙;Ⅳ.足够高的相对运动速度;Ⅴ.连续、充分地供给合适黏度的润滑油。

单项选择题When Maria knows she will be a governess for the family, she feels __________.A. happy and freeB. surprised and reluctantC. indifferent and carelessD. voluntary and well-prepared

单项选择题通常为了提高边界润滑的效果，在润滑油中可加入______。