He can use the method of gradient descent, which involves looking at the steepness of the hill at his current position, then proceeding in the direction with the steepest descent (i.e. downhill).
他可以使用梯度下降法，该方法涉及到察看在他当前位置山的陡峭程度，然后沿着负陡度（即下坡）最大的方向前进。