26、根據相律(phase rule)及水之相圖，在三相點(triple point)上的自由度為： (A) 0 (B) 1 (C) 2 (D) 3。

10、 In Figure 10, a horizontal force of 500 N acts on a block of weight 1.5 kN placed on an inclined plane. The coefficients of friction between the block and the plane are μs =0.25 andμk = 0.20 . What is the actual frictional force? (A) 200N (B) 500 N (C) 300 N (D) 450 N。