随着国内轿车工业的迅急发展，人们每天坐在汽车里的时间越来越长，而车内的空气质量状况也成为影响健康的重要因素之一。

下图为中国科学院所属理化环境分析研究中心发布的《国内汽车空气质量报告》中的测试结果（选取使用年限不同的50款市场上常见的车型进行检测）。

这份空气质量报告，无疑为我们敲响了警钟。

车内空气污染到底来源于哪里？下表列举了车内空气污染的源头及主要污染物。

如何改善车内空气质量呢？下面是一些常见的做法。

① 开窗通风：通常情况下，开窗通风是改善车内空气质量最有效的方法。

② 臭氧消毒：通过臭氧的氧化性可以去除一部分有害气体。

③ 安装车载空气净化器：某品牌空气净化器的工作原理如下图所示，空气通过HEPA过滤材料，清理空气中的尘埃及细小颗粒物，再通过活性炭的协同作用，吸附异味；甲醛在蜂窝状高效催化剂的作用下和氧气反应转化为二氧化碳和水，具有不产生二次污染的优点。

为满足人们对健康生活的追求，提高人们的生活品质，一些新技术、新材料也会不断地优化和使用。

依据文章内容，回答下列问题。

D植物的曲线表明：这段时间内随光照强度增大，其____  作用强度也增大。

C

Liang Xianghua, a 22-year-old girl from Guangxi University, has been well-known in China for her sand painting since her first work was used by CCTV.     "Sand paintings really attracted me while I was watching a video performance, I was surprised by how this artwork melted people's heart in minutes" said Liang. "I fell in love with the way the sand pictures, music and the light combined（融合）with each other to make a flow of emotion（情感）. You can express things freely."

In order to master the skills, Liang practised for several hours every day. She said that she couldn't even do the first step well of throwing sand onto the glass. But she didn't give up.     After finding success with her first show, she was invited to do many performances. This made her quite tired. She decided to give a stop and focus on her study. But an invitation from Malaysia changed her mind just as she was about to wash the sand from her hands. This spring, she was invited by a Malaysia middle school to give a performance. Liang didn't want to do a live show, but agreed to do a video for the school, showing its development over the years.     She received praise for her work and the performance was described as an eye-opener for the students. This made her wonder if her art would be more meaningful if she made it for the poor students.     As a volunteer this time, she plans to take part in a summer programme offering help to pupils in a mountain area, and give the most wonderful show in her life.

下列山地对冬季风南下有明显的阻挡作用，并形成山地两侧不同的气候特点的是（　　）