3 條科學的問題 ( 英文 ) 急急急 !!!

[匿名]

2008-04-15 11:21 pm

3 條科學的問題 ( 英文 ) :

1. Why is aluminum used instead of steel in building airplanes ?

2. Why are silver compounds used in photography ? Name two nonmetals
extracted from seawater that are also part of these compounds .

3. Like selenium , chromium is poisonous butis needed in trace amouts in
your diet . How does this information apply to the safe use of
vitamin - mineral pills ?

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** 回答時的文法不要錯 ...

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回答 (1)

用戶7369

2008-04-16 3:16 am

✔ 最佳答案

1. aluminium is light. it means it is not heavy.
it is important because the weight of an aeroplane will be
very high if it is made of steel which has high density.
so much fuel has to be used and so more money has to be
spent.
2. silver compound is sensitive to light.
so it is used in photography.

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3 條 科學 的問題 ( 英文 ) 急急急 !!!

回答 (1)

3 條科學的問題 ( 英文 ) 急急急 !!!