Đáp án A Điều gì sẽ xảy ra nếu một cây tơ hồng bắt đầu phát triển nơi mà không có cây trồng khác xung quanh? A. Nó sẽ sớm chết. B. Nó sẽ mọc rễ sâu hơn. C. Nó sẽ thu hút các cây khác. D. Nó sẽ bao phủ toàn bộ diện tích đất. Thông tin ở câu thứ 2 của đoạn 3: 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. Tuy nhiên, một cây tơ hồng mới phải tìm được vật chủ nhanh chóng. Nếu nó ko đánh hơi được vật chủ tiềm năng trong vài ngày, Nó sẽ khô và biến mất - ngay cả khi có rất nhiều nước xung quanh.
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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