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遗传学中所说的F2仅指F1自交产生的后代。
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若具有n对表现独立遗传相对性状差异的两亲本杂交，在完全显性的情况下，其F2代中表现型有______种类型，表现型的分离比例为______。
Feed the World with Potatoes1 As food prices continue to rise rapidly, there is growing concern about the effect it will have among the world"s poor.2 Increasingly, experts are looking to the potato as a possible low-cost solution to feeding the hungry. To emphasize the issue, the United Nations has called the potato "a hidden treasure", and named 2008 the International Year of the Potato. Here"s how potatoes could end the food crisis.3 The potato matures more quickly, on less land and in harsher climates than most other major crops. Up to 85 percent of the plant is eatable, compared with around 50 percent of cereals. Its broad adaptability to a wide variety of farming systems is also noteworthy.4 Potatoes are an excellent source of complex carbohydrates ( 碳水化合物), which release their energy slowly, and have only 5 percent of wheat"s fat content. They contain only a quarter of the calories of bread and, according to the Potato Center, when boiled, potatoes have more protein and nearly twice the calcium (钙) as corn. Additionally, they are good sources of vitamin C, iron, potassium (钾) and zinc (锌).5 The Food and Agricultural Organization recently surveyed food price inflation in over 70 of the poor countries. Cereal price inflation was much higher and far more widespread than for potatoes. A significant factor behind the potato"s affordability is the fact that unlike other agricultural products, the potato is not yet a global commodity, and has therefore not attracted speculative investors. Raw potatoes are heavy and can rot during transit, so global trade has been slow to take off. Also, potatoes are susceptible (易受影响的) to infection with disease, hindering (阻碍) export. According to analysts" estimates, less than 5 percent of potatoes are traded internationally, with prices driven primarily by local tastes instead of international demand. Many people eat potatoes because ______.
The course gives you basic instruction in car maintenance.
根据下面的文字说明写一篇450字左右的应用文，要求包含标题、正文、结尾语、落款等几个要素。请你以会议秘书的名义写一份备忘录上呈公司，文中严禁出现任何与考生真实身份有关的信息。中国长城公司(简称甲方)与××国××公司(简称乙方)的代表，于201×年×月×日在××市甲方总部就兴办合资项目进行了初步协商，双方交换了意见，并做出有关承诺。为便于将来继续洽谈，形成备忘条款如下：……
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