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258817This article discusses many of the （） causes of chronic diseases , e.g. unhealthy diets, sedentary lifestyles, and tobacco and alcohol consumption.

258818The three-year draught has caused wide spread （） in that underdeveloped country.

258819Dr. Hanson was invited to give a lecture to （） the 20-year anniversary of the 9/11 attacks.

258820In a lecture given to small business owners, Dr. Smith recommended five effective ways to unlock their employees’ full （）.

258821The discovery of vaccines has led to the near （） of several important diseases and has had a tremendous impact on health for a relatively low cost.

258822The Covid-19 pandemic has （） the development of video conferencing, remote communication, cyber-security etc.

258823Hackers find voting machines used throughout the US are （） to attack.

258824Software developers must pay extra attention to each application in order to find and （） security problems.

258825The （） effects of private tutoring include distortion of the mainstream curricula, pressure on young pupils etc.

258826It’s perfectly natural for Americans, whether Republicans or Democrats, to be （） about government spending.

258827A study found that a child living in Birmingham, England, had his or her life?reduced by approximately 7 months due to （） to toxic air!

258828The service allows consumers to （） cash into their Amazon account in advance, which is a new payment option of the e-commerce giant.

258829More than 97% of the participants found the course to be useful and （） .

258830He argues that it’s essential to solve a （） problem first because by doing that you’ll eliminate a root cause of other problems.

258831All personnel involved in the company’s decision making should have an （） understanding of the company’s strategies, markets and competitors etc.

258832A （） person often worries that something may be dangerous or unwise, so he/she acts very carefully or does things only after a lot of thought.

258833Any type of adult care facility will be held （） for the health of the patients who are left in their care.

258834Discrimination is systemic, not only in the United States but the world over and it is entirely （）.

258835In the play, we see how a series of （） decisions made by Romeo and Juliet lead them to kill themselves.

258836If the environment poses challenges for which the animal has no corresponding adaptation, then functional problems may （）.

258837The software has a new feature, “Digital watermarking”, which can help companies （） security problems caused by lost or stolen devices.

258838It is important to decide if potential roommates have （） personalities and living habits.

258839According to Pittsburgh Public Security, as the policeman （） the vehicle?, the driver ran the car and struck one policeman’s left foot.

258840His arms felt heavy and his heart hammered in his chest as he （） at his opponent, preparing himself for the attack to come.

258841Three vacant buildings （） Tuesday on the South Side after a storm dumped a foot of snow in Chicago.

258842（） work is a highly important type of employment that involves the provision of essential services that support the operations and survival of companies.

258843The little known truth is that lack of clean and （） drinking water is the second largest worldwide killer of children under five.

258844One major issue we are facing now is how to produce more food in a world of （） resources.

258845A new law required associations that use freelancers in California to reclassify these workers as full-time employees （） to employee benefits.

258846Our study examines how emotional feelings （） by a large pool of TV commercials influence the brand evaluations of adult consumers.

258847Children, elderly and pregnant women are the most vulnerable to the （） effects of air pollution.

258848Unfortunately, there are times in which a medical professional’s services result in the harm of a patient instead of their （）.

258849Drug companies, hospital staff, technicians, etc. can be held （） for errors which result in the harm of a patient.

258850Vaccine supply is beginning to （） demand in the United States, so public health officials are getting creative in order to encourage people to take the vaccine.

258851One way to recognize employees is to offer them （） benefits such as pay raises and bonuses.

258852Some companies （） long-serving employees with shares in the business when they retire.

258853Many how-to books about job interview advise you to （） into the room confidently and impress others with your qualities.

258854Even without knowing all the details, readers are often able to （） the direction the author is going to.

258855植物根系吸收矿质有哪些特点？

258856植物缺素病症有的出现在顶端幼嫩枝叶上，有的出现在下部老叶上，为什么？举例加以说明。

258857植物必需元素的一般作用有哪几个方面？试举例说明。

258858无土栽培的营养液主要由水和（）及辅助物质组成。

258859作物对缺乏矿质元素最为敏感的生长发育时期称为需肥临界期或（）临界期，如禾本科作物的幼穗分化期。

258860通常白天硝酸还原速度显著较夜间快，这是因为白天光合作用产生的（）能促进硝酸盐的还原。

258861溶质随水分向根流动是集流运输，而离子从高浓度向低浓度的分子运动是（）运输。

258862根系是陆生植物吸收矿质元素的最主要器官,它吸收矿质的部位和吸水的部位都是根尖未栓化的部分，其中（）区是吸收矿质离子最快最多的区域。

258863任何植物,假若培养在某一单盐溶液中，不久即呈现不正常状态，最后死亡，这种现象称为。

258864细胞膜内外的电势梯度（差）可以用（）测定。

258865离子通道特性可用（）技术测定。

258866离子通道是质膜上构成的圆形孔道，横跨膜的两侧，负责离子的单向跨膜运输。

258867植物需要均衡地吸收各种必需元素，才能正常发育和完成生活史，当缺少某种必需元素时就会发生缺素病状，而症状的出现部位与元素能否（）有关。

258868植物老叶出现黄化，而叶脉仍保持绿色是典型的缺症。

258869氮肥施用过多时，抗逆能力减弱，成熟期。

258870小麦穗未授粉、灌浆，颖壳张开呈“亮穗”等现象，这可能是缺（）。

258871被称为生命元素的是（）。

258872可被植物吸收的氮素形态主要是和硝态氮。

258873氮是构成蛋白质的主要成分，占蛋白质含量的16%～%。

258874必需元素在植物体内的生理作用可以概括为四方面：(1)物质的组分，(2)植物生命活动的调节者，(3)起电化学作用；（4）作为信使物质。

258875必需元素是指对植物生长发育（）的元素。

258876除了碳、氢、氧三种元素以外，植物体内含量最高的元素是。

258877植物体中，碳和氧元素的含量大致都为干重的%。

258878矿质元素中植物必需的大量元素有种。

258879一般说来，微量元素占植物体干重的范围在10-5%～10-2%。

258880高等植物一定比低等植物体内大量元素的含量高。

258881缺镁最明显的病症是叶片贫绿，其特点是首先从下部叶片开始，往往是叶肉变黄而叶脉仍保持绿色，这是与缺氮病症的主要区别。

258882吲哚乙酸的前体是色氨酸，而锌是色氨酸合成酶必要组成元素，故缺锌时会影响生长素合成，导致植物幼叶和茎的生长受阻，产生所谓的“小叶病”和“丛叶病。

258883钠和钾是同一簇元素，故可以完全代替钾的作用，提高细胞的渗透势。

258884盆栽水稻在缺氮、磷、钾、镁时就表现在老叶上，缺钙、铁时就表现在嫩叶上。

258885氮、磷、钾、镁、锌、钠、氯、钼等元素在植物体内易于运转，可多次再度利用，缺素症状首先表现在较老的叶片或组织上。

258886植物主动吸收矿质过程不一定需要利用呼吸作用释放的能量，但必须逆电化学势梯度吸收。

258887虽然植物对水份和矿质吸收比例不同，但在农业生产上可以通过以水调肥，肥水互促，以肥济水等栽培措施提高作物肥水利用效率。

258888植物吸水和吸收矿质的数量会因植物和环境条件的不同而变化很大，两者吸收的机理不同，矿质吸收并不与水分吸收也不成比例。

258889在一定范围内，根系吸收矿质元素的速度，随土壤温度的升高而加快，当超过一定温度时，吸收速度反而下降。

258890植物体内的亚硝酸盐迅速被还原，很少在植物体内积累，这是因为植物组织中亚硝酸还原酶的数量大、活性高。

258891硝酸还原酶的活性可作为植物利用氮素能力的指标。

258892在不同生育期有一个时期施用肥料的营养效果最好,这个时期被称为植物营养最大效率期。一般作物的营养最大效率期是营养生长时期。

258893豆科作物如大豆、豌豆、花生等需要氮肥很多，因此，可以多施一些氮素。

2588941860年萨克斯和诺普相继发表了应用十大化学元素的无机盐配制成营养液，栽培植物获得成功，称它为水培。

258895我国无土栽培起步较晚，但目前在多处建立了无土栽培试验场，并正逐渐推广扩展。

258896植物体内的离子跨膜运输根据其是否消耗能量可以分为主动运输和被动运输两种。

258897施肥促使增产的原因主要是直接作用。

258898水稻植株瘦小，分蘖少，叶片直立，细窄，叶色暗绿，有赤褐色斑点，生育期延长，这与缺磷有关。

258899必需元素中Ca2+离子可以与CaM结合，形成有活性的复合体，在代谢调节中起“第二信使”的作用。

258900果树“小叶病”是由于缺硫的缘故。

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