题干

为防止汶川地震灾区的病菌传播,防疫人员大量使用了“漂白粉”来杀菌消毒, “漂白粉”的有效成分为次氯酸钙[化学式为:Ca(ClO)2]。请回答:
(1)次氯酸钙中金属元素是____ (写元素符号);钙、氧、氯三种元素的质量比为____ 。
(2)次氯酸钙中氯元素的质量分数是 ____ (精确到0.1%)。
(3)若灾区饮用水每50kg至少需要漂白粉250g,则消毒一桶水(约20kg)至少须加漂白粉____ g。

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Ca,40:32:71,49.7%,100

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根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

How to find the perfect career

    Too many people are not satisfied with their professional career (事业) and are “stuck” in situations that do not make them happy. Here are some wonderful actions you can take to begin the path to a truly happy career.

Talk to your friends.

    Ask them, “what do you think I am best at”, or “what do you think I enjoy doing most”. ____However, their advice may help you decide what you should do.

____

    Read some interesting magazines, books, newspapers or novels. They will give you a constant flow of ideas and keep the mind rich.

Talk to the happiest and most successful people you know.

    ____ Be serious with your questions. And see if there is anything you can learn from them. Have these people become your teachers and friends.

Keep a journal(日记).

    Writing down your ideas is an important practice for your career growth. ____You never know when great ideas will come to your mind!

Develop patience.

    You may want a change in your career right now. ____Anyway, doing the practices mentioned above will bring about the right chance much faster.

A. Read as widely as possible.

B. This may seem like a strange conversation at first.

C. Ask them how they realized their dreams.

D. Changing careers can be very difficult.

E. Talk to your family members.

F. But it is necessary to be patient and wait for the right chance to come.

G. Carrying a notebook with you at all times is also a great idea.