“小小竹排江中游,滔滔江水向东流.”这是电影《闪闪的红星》插曲中的两句歌词,那么如果小船要横渡江水,乘船的人就要面临几个问题:怎样航行最省时间?怎样航行最省行程?如果面临险滩暗礁,如何才能轻松而又安全地避过呢?这既是生活中的实际问题,也是运动合成与分解中的典型问题,更是高考的重要考查内容,下面分别进行研究. “This is the second of the lyrics from the episode of the movie” The Sparkly Red Star ", so if the boat crosses the river, the person on board will face several problems: How? How to sailing the most provincial schedule? How to avoid easily and safely if faced with the dangerous beach reef? This is not only a practical problem in life, but also a typical problem in the synthesis and decomposition of movement. Examine the content, the following were studied.