sentences: sliding is a kind of movement & a rock is slided across the frozen pond -> a stone is moving on the frozen lake a rock is moving on the frozen pond  a rock is moving on the frozen pond & friction occurs when two objects move against each other & a stone is a mean of preposition & a frozen pond is a kind of object -> friction will occur between the rock and the  frozen pond friction will occur between the rock and the  frozen pond  slip will occur between the stone and the  frozen lake & a rock is a kind of object & friction causes the speed of an object to decrease -> friction will cause the speed of the rock to decrease