题目内容

【题目】我国某边防站(海拔4900米)的驻防官兵在艰苦的条件下,为改善生活试种蔬菜。他们先盖起简易阳光房,但种的蔬菜仍不能生长。后来,他们又在简易阳光房中搭架,架上盆栽,终于有了收获。回答下列各题。

【1】盖简易阳光房改造的自然条件主要是( )

A.热量 B.水分 C.土壤 D.光照

【2】在简易阳光房中再搭架盆栽,蔬菜才能生长,解决的问题是 ( )

A.蒸发量大 B.多虫害

C.地温低 D.太阳辐射强

【答案】

【1】A

【2】C

【解析】

试题分析:

【1】简易阳光房对太阳短波辐射几乎是透明体,大部分太阳辐射能够透过简易阳光房使房内增温,但是,简易阳光房,对增温后房内放出的长波辐射却是隔热的,所以达到增温的作用。这是农业生产中改造自然因素最成功的范例。所以,简易阳光房改造的自然条件主要是热量。答案选A项。

【2】在海拔4900米的地方地面温度比较低,虽然,用简易阳光房使温度提高许多,但是,由于大地具有热量交换,地面的温度还是不能适应作物的生长,而在简易阳光房中搭架用盆栽,和地面隔开,盆由于不直接和地面接触,热量交换少,所以就解决了地温低的问题,并且能够最大限度地利用垂直方向的光照。解题时这些道理不一定能够想得这样清楚,最好是用排除法,从材料中所给条件:“先盖起简易阳光房,但种的蔬菜仍不能生长”显然蔬菜仍不能生长,不会因为是蒸发量大小、多虫害、太阳辐射强,因此就只剩下“地温低”一个正确答案。答案选C项。

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【题目】A food chain is a simple way of explaining how each living thing gets its food.For example,a simple African food chain might consist of three parts:(1)trees and bushes;(2)giraffes; and(3)lions.Each link in a food chain is food for the next link.Food chains always start with plants and end with animals.

Plants are at the bottom of the food chain.Scientists call them producers,because they use light energy from the sun to produce food from carbon dioxide and water through photosynthesis(光合作用).Animals,unlike plants,can't produce their own food.Instead,they must eat plants or other animals.This is why scientists call them consumers.

Consumer animals fall into three categories.Herbivores eat only plants.Carnivores eat only other animals.Omnivores eat both plants and animals.In addition to producers and consumers,there are also decomposers.These organisms,such as bacteria and fungi,feed on decaying matter.They help the food chain by speeding up the decaying process that releases minerals back into the soil to be absorbed by plants as nutrients.

Most food chains have only four or five links in them.As you go up a food chain,the amount of energy at each level diminishes,because some of the energy is lost in the form of waste or is used up by the organism at that level.That is why it takes many plants,for example,to feed a few giraffes who in turn feed one lion.

Most animals are part of many different food chains,because they must eat more than one type of food to satisfy their energy needs.All of these interconnected food chains form a more complex structure called a food web.Humans,for example,are at the center of a very complex food web,because we tend to eat many different types of plants and animals.

【语篇导读】 本文是一篇说明文。文章以食物链为话题,分析说明了自然界中动植物相互依存的关系,并提出了食物链中的主体——食草动物、食肉动物和草肉皆食动物。

【1】Which of the following tells us the African food chain?

A.Trees,giraffes and lions live on one another.

B.Giraffes eat lions and lions feed on bushes.

C.Lions live on giraffes and giraffes eat trees.

D.Bushes live on lions and lions eat giraffes.

【2】In the second paragraph,the author is mainly to________.

A.emphasize the importance of the plants

B.compare the plants and the animals

C.present the scientists' different views

D.explain the producers and consumers

【3】The underlined word “diminishes”(in Paragraph 4)probably means________.

A.changes B.decreases

D.disappears D.increases

【4】Those that may lie in the centre of the food chain are______.

A.the omnivores B.the decomposers

C.the herbivores D.the carnivores

【5】What would be the best title for this passage?

A.The types of plants and animals

B.The differences among the living things

C.Three categories of the consumers

D.The food chain in the natural world

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