题干

飞机场内都要配置驱鸟设备的目的是    (    )

A:鸟会影响驾驶员的视线

B:减少鸟的噪声

C:鸟可能会撞毁飞机

D:鸟会影响通讯

上一题 下一题 0.0难度 选择题 更新时间:2014-04-21 07:48:17

答案(点此获取答案解析)

C

同类题2

根据短文内容,从下列A-F选项中选出能概括每一段主题的最佳选项。 选项中有一项为多余项。

A. Wash yourself as often as possible

B. Avoid being in hot sun

C. Keep away from smoke and alcohol

D. The importance of skin

E. Have a balanced diet

F. Be sure to have enough water

    ____When it comes to your skin, there is an important fact that you must keep in mind: Your skin is the largest organ of your body. Therefore, skin health and protection is crucial. Your skin does everything for you. It can keep your body hydrated and regulate your body's temperature.

    Now, here are some helpful tips for you to protect your skin:

    ____Protection against harmful rays from the sun is one of the most important steps that you need to take. With this in mind it is necessary for you to avoid strong sunlight as often as possible. As for sunscreen you need to buy products that contain UVA-1, UVA-2 and UVB protection.

    ____Your diet also has a direct impact on the health of your skin. The most important aspect of your diet in relation to the health of your skin is to make certain that you eat a proper amount of food items that contain the proteins and nutrients necessary for cellular maintenance, repair and regeneration.

    ____Water is also important to the health of your skin. While you certainly have heard it before, it actually is true that you should drink at least eight 8-ounce glasses of fresh water every day. There are many health benefits to be derived from drinking water daily, including maintaining healthy skin.

    ____Finally, when it comes to the health of your skin today and into the future you should avoid smoking all together. In addition, you should drink alcohol only in moderation. Both smoking and excessive alcohol consumption can negatively impact the health of your skin in significant ways.

同类题3

(一)虎——自然保护中的旗舰物种

湘泓

虎作为一个大型动物物种的存在,一般受外界环境的影响较大,所以需要具有相当数量的个体聚集在一定地域内,每个个体也都要拥有一个面积足够大的领域,才能经受住自然的和人为的多种影响的考验,维持正常的繁衍生息。

虎的存在对于维持自然界物种的多样性具有非常重要的意义,凡是有虎的地区,则表明该地既有大面积丰富的植被,又有多种多样的食草动物。因为自然界生态系统中的各种生物所构成的食物链是密切相关的,植物的生长需要很好的能源和物质基础,多种多样的植物提供了生物的初级产物,初级产物的消费者食草动物又产生了生物的次级产物,以食草动物为食的虎则处于整个生态系统物质和能量流动的顶级位置。因此,虎被称为自然保护中的旗舰物种,具有重要的生态价值和科学价值。

现在,由于人类活动的增多和范围的扩大,森林被大面积采伐,垦荒造田,开山修路,以及建设城镇、发展交通等等,不仅造成树种单一,植被稀少,隐蔽性差,使虎能够生存的自然环境越来越小,也减少了其生存所需要的猎物,如鹿、狍、野猪等的数量,再加上人们过度的猎杀,导致虎的数量急剧下降,分布区大大缩小,而且往往被分割成很多相互不接连的孤立的分布点,这样虎的种群之间便失去联系,难以进行正常的繁衍,导致近亲繁殖,降低了遗传因子的质量,最终使种群丧失活力。

因此,为了使虎繁衍生息,必须首先保护好它的栖息地,维持一个良好而稳定的生态系统。我国政府不仅早已将虎列为国家级保护动物,而且先后建立了许多以保护为主的自然保护区,关于虎的研究和保护的工程战略计划,也在全国各地有关部门、研究机构和动物园等全面展开。

虎是自然界重要的历史遗产之一,一旦绝灭,将永远不会再恢复或者创造出来。特别是作为我国特产的虎亚种,华南虎已经到了生死存亡的关头,再不及时挽救,在下一个虎年到来之前,就必然步入巴厘虎、爪哇虎和里海虎的后尘,从我们面前消失,正如世界著名猫科动物专家杰克逊先生所说的:“到了那个时候,就只剩下纸老虎了。”因此,对于虎这一物种来说,我们只剩下最后一个机会了。

    (选自《百科知识》,有改动)