天道留学http://tiandaoedu.com/
2016年5月10日SAT官方每日一题---阅读
为了让我们更好的适应sat考试，sat官网每天都会有sat官方每日一题，下面是小编为您整理的2016年5月sat官方每日一题，是关于阅读的，让我们一起来看一看这道阅读题吧。
Plants, and all other living things, require nitrogen for growth; it is an
essential component of nucleic acids and proteins. Although air is mostly nitrogen, this gaseous form is inaccessible to plants and must be fixed into ammonium to render it biologically relevant. Soil bacteria called rhizobia fix nitrogen, but to do this
they must first take up residence inside the roots of legumes like pea, alfalfa, clover, and soybean.
Soon after a legume begins to grow, rhizobia invade its root hairs and multiply, causing the plant to form specialized organs—nodules—that contain the proliferating bacteria. This symbiotic arrangement benefits both parties: legumes can thrive without nitrogen fertilizers only if they have functional nitrogen-fixing nodules, while the bacteria receive the energy needed to multiply and fix nitrogen from the plant. When
the plant dies, the fixed nitrogen is released into the soil so other plants can use it. This process has significant implications for agriculture, as nitrogen is the most
common nutrient deficient in the earth's soil and, thus, the one most commonly supplied by chemical fertilizers.
Rhizobia are a diverse group taxonomically, genetically, and metabolically. They can be found in distant genera. Their symbiotic trait appears to have arisen independently multiple times by horizontal transfer of genes. However, it is not thought that this horizontal gene transfer is sufficient to confer symbiosis, or to explain the biodiversity of rhizobia. There must be selective pressures preventing or permitting the expression of the acquired symbiosis trait and adaptive mechanisms to deal with these pressures. But neither the pressures nor the measures taken to circumvent them are known.
The underlined word \ (A) connected. (B) linked. (C) useable. (D) pertinent. 答案：C
天道教育 带您走向成功留学之道！ 天道留学http://tiandaoedu.com/
解析：
Choice C is the best answer. The author states that the gaseous form of nitrogen \relevant.\is that the nitrogen must be in a form that is biologically useable or accessible to plants.
为了让我们更好的适应sat考试，sat官网每天都会有sat官方每日一题，上面是小编为您整理的2016年5月sat官方每日一题，是关于阅读的，让我们一起来看一看这道阅读题吧。如果想了解更多关于sat考试的相关信息，请关注天道教育平台的sat考试频道，小编会为大家持续更新信息，欢迎您的访问。
天道六步曲为您进行海外求职服务，我们具体的服务项目如下： 1. 海外求职技能培训--包括简历制作、求职信书写、模拟面试等 2. 指导海外职场生存法则、求职方法和途径
3. 协助搭建海外人际关系网，提供海外求职相关信息 4. 简历进入天道猎头人才库，免费提供海外实习及工作信息
5. 优秀人才经过严格挑选进入天道精英网，分享天道全球资源和事业发展机会
天道教育 带您走向成功留学之道！