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1、精选优质文档-倾情为你奉上高中英语科技类阅读四Animals can move from place to place, but plants cannot. When an animal is under attack, it can run away or fight back. . Plants certainly cannot run away, and they lack teeth and claws. But plants can defend themselves by using both physical and chemical means. Some plants ha
2、ve their own ways to keep animals away. For example, the leaves of the holly plant have sharp spines (刺) that discourage grass-eating animals. Holly leaves on lower branches have more spines than leaves on upper branches. This is because the lower leaves are easier for most animals to reach. . Some
3、plants, such as the oak tree, have thick and hard leaves that are difficult for animals to eat. Some grasses may contain a sandy material; eating such grasses wears down the animals teeth. Many plants also have chemical defenses. Some plants produce chemicals that taste bitter or cause an unpleasant
4、 reaction. Some plants may fight against an attack by increasing the production of these chemicals. When a caterpillar (毛虫) bites a tobacco leaf, the leaf produces a chemical messenger. This messenger sends to the roots the information to produce more nicotine. The higher levels of nicotine discoura
5、ge the caterpillar. Many plants depend on both physical and chemical defenses. A certain plant in China, for instance, has prickly (多刺的) leaves, and each prickle contains poisonous venom (毒液). A single experience with this kind of plant will teach an animal to stay away from it in the future .1. The
6、 holly plant has more spines on the lower leaves because most animals_.A. are not tall enough B. like the lower leaves onlyC. are not clever enough D. can get the lower leaves easily2. To defend themselves, oak trees use_.A. chemical means B. physical means C. bitter chemicalsD. sandy materials3. Ho
7、w does tobacco protect itself against an attack from a caterpillar?A. Its leaves fight against the attack by physical means.B. Its roots send a messenger to discourage the caterpillar.C. Its roots increase the production of nicotine when it is attacked.D. Its leaves produce poisonous sand to drive t
8、he caterpillar away.4. What would be the best title for this passage?A. Plants and Animals B. How Plants Defend ThemselvesC. Attacks and Defenses D. How Animals Eat Plant Leaves BWe experience different forms of the Suns energy every day. We can see its light and feel its warmth. The Sun is the majo
9、r source of energy for our planet. It causes the evaporation(蒸发) of water from the oceans and lakes. Sunlight also provides the energy used by green plants to make their own food. These green plants then provide food for all organisms(生物) on the Earth.Much of the energy that comes from the Sun never
10、 reaches the Earths surface. It is either reflected or absorbed by the gases in the upper atmosphere. Of the energy that reaches the lower atmosphere, 30% is reflected by clouds or the Earths surface. The remaining 70% warms the surface of the planet, causes water to evaporate, and provides energy f
11、or the water cycle and weather. Only a tiny part, approximately 0.023%, is actually used by green plants to produce food.Many gases found in the atmosphere actually reflect heat energy escaping from the Earths surface back to the Earth. These gases act like the glass of a greenhouse in that they all
12、ow energy from the Sun to enter but prevent energy from leaving. They are therefore called greenhouse gases.When sunlight strikes an object, some of the energy is absorbed and some is reflected. The amount reflected depends on the surface. For example, youve probably noticed how bright snow is when
13、sunlight falls on it. Snow reflects most of the energy from the Sun, so it contributes to the low temperatures of winter. Dark-colored surfaces, such as dark soil or forest, absorb more energy and help warm the surrounding air.5. According to the passage, the root cause for weather changes on the Ea
14、rth is _. A. the atmosphere surrounding the EarthB. water from oceans and lakes C. energy from the SunD. greenhouse gases in the sky6. Only a small part of the Suns energy reaches the Earths surface because most of it is _. A. absorbed by the clouds in the lower atmosphere B. reflected by the gases
15、in the upper atmosphere C. lost in the upper and lower atmosphere D. used to evaporate water from the oceans and lakes7. We learn from the passage that _. A. all living things on the Earth depend on the Sun for their food B. a forest looks dark in winter because it absorbs solar energy C. only 0.023% of the energy from the Sun is made use of on the Earth D. greenhouse gases allow heat energy to escape from the Earths surfaceDBCB C CA专心-专注-专业