Đáp án D Cụm “For example”, dòng 19, giới thiệu một câu là ví dụ của A. những cuốn sách giáo khoa tương tự nhau B. kết quả của việc học trên trường C. những công việc của chính phủ D. những rào cản của các môn học trên lớp Giải thích: Thông tin nằm ở câu trước cụm “For example” “The slices of reality that are to be learned, whether they are the alphabet or an understanding of the workings of government, have usually been limited by the boundaries of the subject being taught.” : Những mẩu của sự thật, điều mà đã được học, cho dù chúng là bảng chữ cái hay sự hiểu biết về những công việc của chính phủ, thì đều bị giới hạn bởi rào cản của những môn học đã được dạy.
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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