¡¡¡¡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.
¡¡¡¡1.What does the passage mainly discuss£¿
¡¡¡¡£¨A£© Birds
¡¡¡¡£¨B£© Insects
¡¡¡¡£¨C£© Flowers
¡¡¡¡£¨D£© Perfume
¡¡¡¡2.The orchid is unique because of
¡¡¡¡£¨A£© the habitat in which it lives
¡¡¡¡£¨B£© the structure of its blossom
¡¡¡¡£¨C£© the variety of products than can be made from it
¡¡¡¡£¨D£© the length of its life
¡¡¡¡3.The word "fused" in line 3 is closet in meaning to
¡¡¡¡£¨A£© combined
¡¡¡¡£¨B£© hidden
¡¡¡¡£¨C£© fertilized
¡¡¡¡£¨D£© produced
¡¡¡¡4.How many orchid seeds are typically pollinated at one time£¿
¡¡¡¡£¨A£© 200
¡¡¡¡£¨B£© 2£¬000
¡¡¡¡£¨C£© 20£¬000
¡¡¡¡£¨D£© 200£¬000
¡¡¡¡5.Which of the following is a kind of petal£¿
¡¡¡¡£¨A£© The column
¡¡¡¡£¨B£© The sepal
¡¡¡¡£¨C£© The stem
¡¡¡¡£¨D£© The labellum
¡¡¡¡6.The labellum£¨line10£© is most comparable to
¡¡¡¡£¨A£© a microscope
¡¡¡¡£¨B£© an obstacle course
¡¡¡¡£¨C£© an airport runway
¡¡¡¡£¨D£© a racetrack
¡¡¡¡7.The word "lure" in line 13 is closet in meaning to
¡¡¡¡£¨A£© attract
¡¡¡¡£¨B£© recognize
¡¡¡¡£¨C£© follow
¡¡¡¡£¨D£© help
¡¡¡¡8.Which of following is NOT mentioned as a means by which an orchid attracts insects£¿
¡¡¡¡£¨A£© Size
¡¡¡¡£¨B£© Shape
¡¡¡¡£¨C£© Color
¡¡¡¡£¨D£© Perfume
¡¡¡¡9.The word "their" in line 17 refers to
¡¡¡¡£¨A£© orchids
¡¡¡¡£¨B£© birds
¡¡¡¡£¨C£© insects
¡¡¡¡£¨D£© species
¡¡¡¡10.Which of the following statements about orchids' scents does the passage support£¿
¡¡¡¡£¨A£© They are effective only when an insect is near the blossom.
¡¡¡¡£¨B£© Harmful insects are repelled by them.
¡¡¡¡£¨C£© They are difficult to tell apart.
¡¡¡¡£¨D£© They may change at different times.
¡¡¡¡11.The word "placed" in line 21 is closet in meaning to
¡¡¡¡£¨A£© estimated
¡¡¡¡£¨B£© measured
¡¡¡¡£¨C£© deposited
¡¡¡¡£¨D£© identified
¡¡¡¡12.The word "discrete" in line 24 is closet in meaning to
¡¡¡¡£¨A£© complicated
¡¡¡¡£¨B£© separate
¡¡¡¡£¨C£© inoffensive
¡¡¡¡£¨D£© functional
