此句可改写为some effective measures should be taken to change the situation before things get worse,句子的主语是measures.measures的逻辑主语是采取有效措施的人.someone take some effective measures to ch...是的，你说的非常正确，分析得非常到位。我想问一下，Some effective measures should be takento change the situation before things get worse 到底有没有错？没错，但是不好。语法点是非谓语动词做目的状语的用法，一般高中语法书里就有，将目的状语提前是为了使句子看起来更加匀称。