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   If you think English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven’t you noticed that you have become smarter since you started to learn a language?
   According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles.
   The researchers also found the effect is greater on the younger people who learn a second language.
   A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who only spoke English. They were compared with a group of “early bilinguals(通两种语言的人)”, who had learnt a second language before the age of five, as well as a number of later learners.
   Scans showed that grey matter density（密度）in the brain was greater in bilinguals than in people without___________________. But the longer a person waited before mastering a new language, the smaller the difference was.
   “Our findings suggest that the structure of the brain is changed by the experience of learning a second language,” said the scientists.
It means that the change itself increases the ability to learn.
   Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and maths skills. Having two languages gives you two windows on the world and makes the brain more flexible,” he said, “You are actually going beyond language and have a better understanding of different ideas.”

在探究鱼鳍的作用时，将鲫鱼的某种鳍捆住后放入水中，结果发现鲫鱼游动时不能很好地改变运动方向，由此可以推断被捆绑的鳍是（     ）    

镍氢电池是近年开发出来的可充电电池，它可以取代会产生镉污染的镉镍电池．氢镍电池的总反应式是：$\frac{1}{2}$ H₂+NiO（OH）=Ni（OH）₂据此反应式判断，下列叙述中正确的是（   ）

某些媒体报道“转基因植物油对人类的健康不利”，也有专家说“转基因植物油是安全的”，到底是否安全呢？某班初二学生针对这一问题进行了如下探究实验．

（一）实验器材：普通植物油，转基因植物油，稻谷若干，小白鼠若干，两个规格一样且空间足够大的铁笼等．

（二）该同学提出的问题：转基因植物油对人类的健康是否有影响．

（三）实验过程：

（1）将两个铁笼分别贴上甲组和乙组标签，选取两只身体健康状况良好、大小一致、性别相同的小白鼠，分别置于甲、乙铁笼中．

（2）称取一定重量的同种稻谷平均分成两份，分别拌适量且等量的普通植物油（A料）和转基因植物油（B料）待用．

（3）甲组饲喂适量A料，乙组饲喂____ B料．

（4）饲喂一段时间后，观察并记录甲、乙两组小白鼠的生长状况．

（5）预测实验结果和结论：

①若两组小白鼠的生长状况有明显差异，则说明转基因植物油对人类健康____ （填有或无）影响．

②若两组小白鼠的生长状况无明显差异，则说明转基因植物油对人类健康____ （填有或无）影响．

（四）请根据上述实验设计回答下列问题：

（1）请你为该同学做出假设，你的假设是：____ 

（2）该同学设置甲组的目的是对照，该实验的实验变量是____ 

（3）该实验选取小白鼠的数目过少，会增大实验的____ ，导致实验结论可信度不高．

它利用“冷战”的阴影，把“遏制”共产主义的计划与制造商、出口商的热情融为一体。这里的“它”是指