已知 $\frac{x}{y}=\frac{1}{3}$，那么$\frac{x}{x+y}$=____ ．

    It's sunny today. The sun is shining(照耀)in the sky and it's very hot. Nancy goes to the train station(车站)to meet her mother at noon. She walks in the street. There are no trees and she's fat. So she feels very hot. But she doesn't find (发现)a boy walking behind her. And she meets a friend and says "Hello" to him. "Who's the boy behind you?" asks(问) the man. Now she sees the boy. She is angry and asks, "Why(为什么) do you walk behind me, boy?" there's no shade(阴凉处) in the street, you know" answers the boy. "It's cool behind you, I think(想)."

爱默生有句名言：“人生最美丽的补偿之一，就是人们真诚地帮助别人之后，同时也帮助了自己。”对此理解正确的有（     ）
①帮助别人，别人就得帮助自己
②合作有利于倡导关爱他人、助人为乐的社会风尚
③助人与自助是人类合作的一种方式，帮助别人就是帮助自己
④人生最美丽的补偿应该是在帮助别人之后获得必要的物质回报

下列关于亚洲海陆位置的描述中，不正确的是（    ）

①东临太平洋，北临北冰洋 ②位于太平洋西岸 ③位于北冰洋北面 ④位于印度洋北面，北冰洋南面。