【正文】 hip. The trees provide the bacteria with food, in the form of fallen leaves and other material, and the bacteria break this material down into the nutrients that the trees need to survive.One of the most remarkable things about rainforest plant life is its diversity. The temperate rainforests of the Pacific Northwest are mainly posed of a dozen or so tree species. A tropical rainforest, on the other hand, might have 300 distinct tree species.All Creatures, Great and SmallRainforests are home to the majority of animal species in the world. And a great number of species who now live in other environments, including humans, originally inhabited the rainforests. Researchers estimate that in a large rainforest area, there may be more than 10 million different animal species.Most of these species have adapted for life in the upper levels of the rainforest, where food is most plentiful. Insects, which can easily climb or fly from tree to tree, make up the largest group (ants are the most abundant animal in the rainforest). Insect species have a highly symbiotic relationship with the plant life in a rainforest. The insects move from plant to plant, enjoying the wealth of food provided there. As they travel, the insects may pick up the plants39。s axis, the Northern and Southern hemispheres each spend part of the year tilted away from the sun. Since rainforests are at the middle of the globe, located near the equator, they are not especially affected by this change. They receive nearly the same amount of sunlight, and therefore heat, all year. Consequently, the weather in these regions remains fairly constant. The consistently wet, warm weather and ample sunlight give plant life everything it needs to thrive. Trees have the resources to grow to tremendous heights, and they live for hundreds, even thousands, of years. These giants, which reach 60 to 150 ft in the air, form the basic structure of the rainforest. Their top branches spread wide in order to capture maximum sunlight. This creates a thick canopy (樹冠) level at the top of the forest, with thinner greenery levels underneath. Some large trees grow so tall that they even tower over the canopy layer.As you go lower, down into the rainforest, you find less and less greenery. The forest floor is made up of moss, fungi, and decaying plant matter that has fallen from the upper layers. The reason for this decrease in greenery is very simple：The overabundance of plants gathering sunlight at the top of the forest blocks most sunlight from reaching the bottom of the forest, making it difficult for robust plants to thrive.The Forest for the TreesThe ample sunlight and extremely wet climate of many tropical areas encourage the growth of towering trees with wide canopies. This thick top layer of the rainforest dictates the lives of all other plants in the forest. New tree seedlings rarely survive to make it to the top unless some older trees die, creating a hole in the canopy. When this happens, all of the seedlings on the ground level pete intensely to reach the sunlight.Many plant species reach the top of the forest by climbing the tall trees. It is much easier to ascend this way, because the plant doesn39。 if the information is not given in the passage.For questions 510, plete the sentences with the information given in the passage.NG (for NOT GIVEN) if the statement contradicts the information given in the passage。s plant and animal species.What Is a Rainforest?Generally speaking, a rainforest is an environment that receives high rainfall and is dominated by tall trees. A wide range of ecosystems fall into this category, of course. But most of the time when people talk about rainforests, they mean the tropical rainforests located near the equator.These forests receive between 160 and 400 inches of rain per year. The total annual rainfall is spread pretty evenly throughout the year, and the temperature rarely dips below 60 degrees Fahrenheit.This steady climate is due to the position of rainforests on the globe. Because of the orientation of the Earth39。s branches extend upward, spreading out into the canopy. Eventually, the strangler may block so much light from above, and absorb such a high percentage of nutrients from the ground below, that the host tree dies.Competition over nutrients is almost as intense as petition for light. The excessive rainfall rapidly dissolves nutrients in the soil, making it relatively infertile except at the top layers. For this reason, rainforest tree roots grow outward to cover a wider area, rather than downward to lower levels. This makes rainforest trees somewhat unstable, since they don39。 Lumber for paper and other wood products s tropical rainforests will be wiped out within 40 years.1. Virtually all plant and animal species on Earth can be found in tropical rainforests.2. There is not much change in the weather in the tropical rainforests all the year round.3. The largest number of rainforests in the world are located on the African continent.4. Below the canopy level of a tropical rainforest grows an overabundance of plants.5. New tree seedlings will not survive to reach the canopy level unless ________.6. Epiphytes, which form much of the under story of the rainforest, get all their water and nutrients from ________.7. Stranglers are so called because they ________ by blocking the sunlight and peting for the nutrients.8. Since rainforest bacteria and trees depend on each other for life, the relationship they form is termed ________.9. Plant species are dispersed over a large area with the help of ________.10. As we are still ignorant of millions of unique life forms in the rainforest, defor