题干

以下细胞结构中,不含有磷脂的是的是(    )

A:核糖体

B:内质网

C:高尔基体

D:叶绿体

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答案(点此获取答案解析)

A

同类题2

阅读议论文《寒门贵子,贵在奋斗》,完成下列小题。

    ①古人云:“自古寒门出贵子,从来纨绔少伟男。”在当今社会,这样的观点也许有些片面,但它对于当今处于寒门的青年来说确实是起到了一定的鼓励作用。

    ②那么,谁才是今天社会中的“贵子”?

    ③“贵”并不意味着一定要升官发财,也不意味着必须拥有多么高的社会地位,“贵”代表的是人生进步的可能性以及实现人生价值的机会。富二代、官二代无疑符合传统意义上的“贵”,但如果没有一技之长,不能凭借自身本领干事创业,所谓“贵”也不过停留在人生的浅表。相反,白手起家的寒门青年,凭借自身努力打拼出一片天地,努力创造属于自己乃至整个社会的价值,“贵子”的称谓自然当之无愧。作为哈佛大学优秀毕业生代表之一的中国寒门学子何江,曾讲到自己成功的经验:“每到一个更大的地方、更大的平台,你会发现自己不懂的东西很多,而我相对来说,好奇心比较多,我就会有压力去把它学会,让自己不断补足短处。”

    ④寒门贵子的成功很大程度上与他的刻苦奋斗和拥有的社会信任以及社会支持力量相关。如今,网络也为寒门青年走向成功提供了强大的社会支持力量。一位网名为“搬家小伟”的湖北青年石神伟,凭借一系列高难度健身视频,在短视频分享平台上吸引了超过百万粉丝。这位寒门青年从留守儿童、网瘾少年一路走来,用健身不断磨练和改变自己,传递着积极进取、拼搏向上的正能量,感动了无数网友。今天,许多像“搬砖小伟”这样寒门出生的“网红”,借助网络实现了自身的价值,也为社会进步传递着正能量。

    ⑤当今社会,家庭出身、教育背景和工作平台确实影响着一个人的成长路径。但寒门贵子的诞生,在于自己的打拼。一篇题为“寒门贵子”的文章中,有这样一句话:“命运给你一个比别人低的起点是想告诉你,你要靠自己去奋斗出一个绝地反击的故事。”在今天这样一个充满无限可能的时代,寒门能否出贵子,很大程度上并不是一个关于“命运”的话题,而是一个关于“奋斗”的故事。

    ⑥由此看来,努力奋斗,成就寒门。

同类题4

阅读理解

A report by UNEP联合国环境规划署(United Nations Environment Programme) says that by 2050, the world's population is expected to reach 9.6 billion and feeding us all will require at least 60% more food than we have ever produced before. What's more, if we can't find out a way to do with it, food shortages (短缺) could be a big problem.

A main purpose of the report is to make people be aware of the importance of this challenge. In the past, food production increase relied on the practices like cutting down trees, using chemicals and wasting water. Today we understand the environmental price of those techniques.

“The question now is how to produce much more food and at the same time avoid all the environmental problems that we had in the past,” Searchinger, a famous scientist said.

We need to develop new ways to produce food. We can no longer cut down trees. Instead, we'll have to protect water and land, and reduce air pollution.

The report also mentions the importance of reducing food loss and wasteAccording to the United Nations, the waste adds up to one-third of all the food we produce —an amount that could feed an additional 2 billion people.

The report also suggests that we make changes in our diet. “You have to eat more efficiently (有 效地),” said Searchinger, “and above all that means eating less meat, and especially reducing the growth of beef.”That's because raising cows is an inefficient way of producing food. Of all the energy that goes onto feeding cows, only about 1% is converted (转换) into food for people.