题干

函数为奇函数,该函数的部分图 像如图所示,分别为最高点与最低点,且,则该函数图象的一条对称轴为(   )

A:

B:

C:

D:

上一题 下一题 0.0难度 选择题 更新时间:2016-11-17 05:07:11

答案(点此获取答案解析)

D

同类题1

阅读理解

    You eat food and drink water, right? Skipping Rocks Lab is changing how you and your future generations will have water. Have you ever thought you could eat water? Think again, this is actually happening somewhere in the world.

    The group at Skipping Rocks Lab has made a water bottle you can eat. The product is called Ooho. Unlike plastic bottles, Oohos are neither tall nor hard. They look more like bubbles, or small, round, clear balls. They can hold liquid inside. People who drink Oohos can be surprised: the outside bursts in the mouth.

    Rodrigo Garcia Gonzalez is with Skipping Rocks Lab. He explains that the outside, or the membrane, of Ooho is made of seaweed, a plant that grows in the ocean. “It's a membrane made of seaweed that can contain water or any kind of liquid. It's made from an extract (汁) of the brown seaweed.”

    The Ooho membrane is tasteless, and you can eat it. The company says even if you throw away the membrane, it will break down in about four weeks. Gonzalez says the membrane is strong, and good for the environment.

Every year, billions of plastic water bottles are thrown away, polluting land and waterways around the world. The typical water bottle made of plastic can take hundreds of years to degrade.

    Lise Honsinger is also with Skipping Rocks Lab. “Most people just grab a bottle of water, hold it for five minutes, drink it, and throw it away. How can that then exist for 700 years? So, yeah, this is absolutely a solution to that. We are very purist: we don't want to see this packaged in plastic.”

    There are limits to the Ooho. It cannot be refilled. Each bottle is small. And Oohos do not store for more than a few days. The Skipping Rocks Lab is working on those issues. “We're still working on things like extending the shelf life, looking at different options in terms of thickness, if we want to make one that stands up more, or more flexible for marathons where people just want to eat it whole.”

    Right now, Skipping Rocks Lab can make only a few thousand Oohos a day. But it is developing new technology that could increase that number to hundreds of thousands.

    I'm Caty Weaver. Kevin Enochs wrote this story. Anne Ball adapted it for Learning English. Kelly Jean Kelly was the editor.

同类题4

阅读《地球大气圈》节选文字,完成后面小题。

       ①我们翘首望天,似乎高不可及。其实我们所看见的这个“天”,本是“地”的一部分——地球大气圈的低层。它的高度不过十几公里,宇宙火箭很容易就穿越了这个高度,这时再回顾地球,蓝天却已跑到我们的脚下,似轻烟,似薄雾,更仿佛是一层蔚蓝色的软纱裹在地球的表面。

       ②大气圈看起来仿佛空若无物,实际上是壁垒森严,将地球重重包住。岂止是面纱,简直是屏障,是铜墙铁壁,对地球起着重要的保护作用。

       ③1976年,在我国吉林省落了一场陨石雨,成为自然界罕见的珍闻。假使没有大气,这种从天而降的陨石将成为家常便饭,给地面造成极大毁坏。正是由于大气圈的保护,高速冲来的陨石因与大气剧烈摩擦,减慢了速度;并因摩擦产生的高热影响,绝大部分陨石在100多公里的高空就化为灰尘和气体,只有极少数到达地面,而且已是强弩之末,一般不会造成什么危害了。

       ④从天外向地球袭来的还有强烈的紫外线。假使没有大气,过多的紫外线将使地球上的生命无法生存,是大气圈保护了我们。在大气圈中离开海面20-35公里这一带含臭氧较多。所谓较多,也不过占到四百万分之一左右。但这点臭氧已足以使大量紫外线被吸收,才使得地球上各种生物免受过多的紫外线伤害;剩下少量的到达地面,对我们来说有杀菌防病作用,反而变得无害而有益了。

       ⑤那些极其稀薄的为地球磁场所控制的带电粒子组成的高层大气,也有保护地球的作用。它能使宇宙中那些以高速冲向地球的粒子流偏转方向。

       ⑥地球大气圈的存在,不仅保护了我们,还是生命得以发生和发展的重要条件。假使没有大气,就没有灿烂的云霞,更没有生命的喧嚣,而将是白天酷热,夜晚严寒,天上是黑洞洞的,地下是一片荒凉。