这台空气曲棍球桌的设计让圆盘在几乎无摩擦的表面上滑动。

This air hockey table is designed for the puck to slide on a nearly ___frictionless surface.

新系统使在线支付变得无比顺畅，没有任何障碍。

The new system makes online payments completely ___frictionless, with no obstacles at all.