Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions
Dodder is an unusual and unwanted plant that attacks other plants. Except for its flowers, the plant looks like spaghetti noodles. Its almost leafless, thread–like stems hang down atop other plants that dodder needs to stay alive. Dodder does not produce its own food. Instead, it steals it from other plants. It feeds by sucking juices from the plant it is wrapped around, often making its host very weak or even killing it. Dodder can find other plants by their smell. When a dodder seedling starts growing, it follows the scent of plants it prefers, like tomato plants, potato plants, or other farm crops. Unlike most plants that usually grow in the direction of light or warmth, a dodder plant will grow in the direction of, for example, tomato odor––if a tomato happens to be growing nearby. However, a young dodder plant must find a host plant quickly. If it cannot catch a whiff of a potential host within a few days, it will dry up and disappear—even if there is plenty of water around. Once it finds a host, the young dodder plant will attach itself to it and start growing faster. At that point, the dodder plant will drop its root. Dodder is thus a difficult weed to manage and a real headache for farmers. When it does get out of hand, dodder can greatly reduce a farmer’s harvest or even destroy crops completely. Before sowing their produce, farmers in warm parts of the world often check to make sure no unwanted dodder seeds have intermingled with their crop seeds. This is a good way to stop dodder plants from sneaking their way into a crop field.
Đáp án C Chủ đề chính của đoạn văn là gì? A. Một loại cây nông nghiệp mới B. Cây có hại cho con người C. Những khả năng đặc biệt của một loài cây nguy hiểm D. Những cải tiến gần đây về phương pháp nuôi Ý chính của đoạn văn là về cây tơ hồng, những khả năng đặc biệt của nó được thể hiện trong đoạn 1: Its almost leafless, thread–like stems hang down atop other plants that dodder needs to stay alive. Dodder does not produce its own food. Instead, it steals it from other plants. It feeds by sucking juices from the plant it is wrapped around, often making its host very weak or even killing it.
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions
Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator. To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times. Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.
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