From 26 to 28 October, 20081Wuxi experienced a snowstorm that was rare in history. "The snowstorm is merciless, and people unite to fight it." All parties are very active.

Putting grass mats on the frozen ground in winter is to increase the roughness of the contact surface to increase the friction force under the condition of constant pressure, so as to achieve the purpose of anti-skid;

As soon as raindrops touch the ground, they freeze and change from liquid to solid. This is solidification.

So the answer is: increase; solidify