题干

下列说法正确的是(   )

A:某有机物燃烧只生成CO2和H2O,且二者物质的量相等,则此有机物的组成为CnH2n

B:一种烃在足量的氧气中燃烧并通过碱石灰,减少的体积就是生成水蒸气的体积

C:某气态烃CxHy与足量O2恰好完全反应,如果反应前后气体体积不变(温度>100℃),则y=4,若体积减少,则y>4,否则y<4

D:相同质量的烃,完全燃烧,消耗的O2越多,则烃中氢元素的百分含量越高

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答案(点此获取答案解析)

D

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Every day, life is made and lost. Every day, life goes on. Every day we experience some of the most important parts of life and may not even realize it: love, generosity, and perseverance. These values aren't just important to us, they make the world what it is.
Scientists say that the gravity makes the world turn, but some people say that love makes  it  go around. Love can be found anywhere: in families, friends, even strangers. Even if you can't see it, you know it's there.
Love may connect people all over the world, but what would the world be without generosity? Whether after a national disaster or a school fund raiser, one thing is certain--- it is better to give than to receive. Generosity is found everywhere and whether it's a large or small act, it makes a difference. Most of all, generosity is not something you need any qualifications(资格)for, and no matter what you do, it can make a difference. Sometimes, though, it takes effort to be generous, which leads us to perseverance.
Founding a country, riding a bike, or finishing a novel, these are all finished with perseverance. Perseverance is the one thing that can help us achieve whatever we want. It is what helps scientists discover cures for illnesses, and athletes become winners. You may fail, but every time you make a mistake, that's one less to make the next time.
There is an infinite(无限的) number of things we value. But without love, generosity, and perseverance, we just don't think that our lives or the world would be the way it is.