题干

下列实验现象描述正确的是    (   )。

A:氯化氢与氨气相遇,有大量的白雾生成

B:用铂丝蘸取硫酸钠溶液灼烧,火焰呈黄色

C:SO2通入品红溶液,红色褪去,再加热,红色不再出现

D:氯化亚铁溶液与无色的KSCN溶液混合,溶液呈红色

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B

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    Are you nervous about climbing because you think it's too dangerous?Do you feel you're not fit enough to climb?Do you know how to start climbing?

    Let's consider the idea that climbing is dangerous.Being afraid is natural,but if you use suitable ropes and other climbing equipments you will feel completely safe.Climbers are usually very careful because they know what they are doing is dangerous.Accidents may happen,but when they do,they tend to attract a lot of publicity.As a result, people think there are many more accidents than there are in reality.

    You cannot expect to start climbing straight away.Climbing is a challenge and challenges take time.It is necessary first of all that you achieve a good level of fitness.Begin as soon as you become interested in climbing—go to the gym,go swimming,take up jogging and continue to do so throughout your training period.

    Discover as much as you can about climbing.Visit the library and find books especially for beginners or buy climbing magazines and look for articles which describe your situation.Look up information on the Internet.Find out about equipment,methods and places to go.

    Next,take a course on a climbing wall.There are plenty of climbing walls all over the country which have trained and qualified people as instructors.Call your local leisure centre to find out if there is one in your area.These training sessions are a quick way to get experience and you are likely to meet other beginners.After this,you can do an outside course or join a club where you can meet climbers of all abilities and eventually join in group-climbing events.

    At first you may not understand the importance of a good training period,but after you have completed your first climb and you are standing safely at the top of a rock feeling thrilled,then you will know it was the right thing to do.