打水漂时,石头为什么在水上面不沉入水中

下列词语中，没有错别字的一组是 A．驾驭挡箭牌故伎重演风马牛不相及 B．湮没打水漂缪种流传从善如登，从恶如崩 C．端详敲竹杠金榜题名一言既出，四马难追 D．谛造老皇历言简意赅毕其功于一役

帮做一篇~任务型阅读不甚感激
做完一定给100分~因为现在给的话没准分会打水漂~
Be careful what you say around your dog.It might understand more than you think.
A border collie named Rico recognizes the names of about 200 objects,say researchers in Germany.The dog also appears to be able to learn new words as easily as a 3-year-old child.Its word—learning skills are as good as those of a parrot or chimpanzee(黑猩猩)
In one experiment,the researchers took all 200 items that Rico is supposed to know and divided them into 20 groups of 10 objects.Then the owner told the dog to go and fetch one of the items and bring it back.In four tests,Rico got 37 out of 40 commands right.As the dog couldn't see anyone to get clues,the scientists believe Rico must understand the meanings of certain words.
In another experiment,the scientists took one toy that Rico had never seen before and put it in a room with seven toys whose names the dog already knew.The owner then told Rico to fetch the object,using a word the dog had never heard before.
The correct object was chosen in seven out of 10 tests,suggesting that the dog had worked out the answer by process of elimination (排除法) A month later,Rico remembered half of the new names,which is even more impressive.
Rico is thought to be smarter than the average dog.For one thing,Rico is a border collie,a breed (品种) known for its mental abilities.In addition,the 9-year-old dog has been trained to fetch toys by their names since the age of nine months.
It's hard to know if all dogs understand at least some of the words we say.Even if they do,they can't talk back.Still,it wouldn't hurt to sweet-talk your dog every now and then.You might just get a big,wet kiss in return!
56.What’s the best title of the passage?(No more than 15 words)
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57.Please explain the underlined "a border collie" in English.
(No more than 5 words)
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58.Why has Rico got a good memory?(No more than 15 words)
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59.What does the writer advise us to do by saying “it wouldn't hurt to sweet--talk...(No more than 10 words)
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60.Would you like to keep a dog as a pet?Why?
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把石头从水面上方放手落进水中,石头直接下沉不会往上跳,但打水漂时则会.
而打水漂只是给石头一个向前的力.分解这时候石头的速度,它有向前和向下两个速度.向下的速度和把它从相同高度放下落进水中时的速度相同,且该石的重力相同,只是增加了一向前的速度,那么石头为什么会向上?

为什么打水漂的时候石头可以弹起来?
通俗一点了 不然我不懂的

下列词语中，没有错别字的一组是（　　） A．表率　一揽子　凭心而论　如堕五里雾中 B．废解打水漂以偏概全坐收渔人之利 C．晦涩吊胃口兼容并包毕其功于一役 D．申辩紧箍咒扬长而去有志者事竞成