据某网上商城数据显示，随着雾霾天气长期大范围持续，空气净化器日益走进普通百姓家庭，售价上涨的走势成为该行业发展的催化剂。不考虑其他因素，能正确反映这种变动传导效应的是（注：D、S为变动前，D1、S1为变动后）（  ）

如图所示边长为a的正方体浸没在密度为ρ的液体中，液体对正方体上表面的压力为F_l，液体对正方体下表面的压力为F₂．试在图中作出F_l、F₂力的示意图．证明液体对正方体上下表面的压力差△F与正方体浸没在液体中的深度无关．

一些科学家测算，由于现代工业的发展，大量燃烧煤、石油、天然气向大气中排放二氧化碳日益增多。二氧化碳能大量吸收地面放出的热量，进而使全球气温有明显变暖的趋势。为了防止这种现象，适宜的方法有（ ）
①立即停止使用煤、石油、天然气等燃料
②积极开发使用新能源
③植树造林，保护好现有的原始森林
④扩大海洋面积，调节气温

根据短文内容，从方框中选择适当的句子填空，使短文意思完整、通顺。

     ____ Some people climbed the highest mountains, some traveled to unknown parts of the world, and some sailed small boats across the largest sea. Now some people begin to look for new excitement(刺激).

     ____ Bungee jumping only lasts a few minutes or even seconds. You jump from a high place, 200 meters above the ground, and there is a rubber band tied to your legs. When you jump down, the rubber band pulls you up. About 2,000,000 people around the world have tried bungee jumping.

     ____ Some scientists (科学家) say that it is because modem life has become safe and it is not interesting. ____ They had to go out and look for food, and life was like a fight but was interesting.

     ____ They live and work in safe places, buy food in shops, and there are doctors and hospitals to look after them if they become ill.

了解自然
自然环境是由地形、气候等自然要素相互联系、相互制约形成的，是人类赖以生存和发展的自然基础．据此完成下题．
下列选项中可以预测一个地区气候的是（ ）