我国修建青藏铁路，对穿越可可西里自然保护区的线路采取了绕路措施，在野生动物活动地区设置通道。这些措施说明我国在现代化建设中坚持                        （   ）  
①保护环境的基本国策      ②可持续发展的持续性原则 
③可持续发展的公平性原则  ④人与自然和谐相处 

    When we talk about paper, we think of newspapers and books. But there is some paper____(use) in many other ways. Only half of____ world's paper is used for books and newspapers. Paper , on____we usually write and draw , is very good for keeping you warm. You have perhaps seen homeless men asleep on a large number of newspapers. In Finland, it is sometimes -40°C in winter. The farmers wear paper boots in the snow. Nothing could be____ (warm).

    Each year, more and more____ (thing) are made of paper. We have had paper cups and plates for a long time. But now we hear that chairs, tables, and even beds can____(make) of paper. With paper boots and shoes, you can also wear paper hats, paper dresses, and paper raincoats____you have used paper cups once, you throw them away and buy new____(one).

    The latest use of paper seems to be paper houses. These are not small houses for children ____(play) in, but real, big houses for people to live in. You can buy a house with three rooms for about 500 dollars. You can put it up by yourself in a few hours____you can use it for about five years.

①已知p³+q³=2 ，求证： $p+q\le 2$ ．用反证法证明时，可假设$p+q\ge 2$ ；

②若$a,b\in R,\left|a\right|+\left|b\right|<1$ ，求证：方程x²+ax+b=0  的两根的绝对值都小于1．用反证法证明时可假设方程有一根 x₁ 的绝对值大于或等于1，即假设$\left|x_1\right|\ge 1$ ；

以下结论正确的是（   ）

已知y是关于x的函数，函数图象如图，则当y＞0时，自变量x的取值范围是（　　）