题干

 ”渤船重工“是地处葫芦岛市的大型造船企业,每年都有巨轮在这里建成下水.钢铁是造船的主要材料之一

(1)钢铁属于____ (填字母).

A.复合材料    B.合成材料    C.金属材料

(2)钢铁易于空气中的____作用发生锈蚀,请你列举一种防止钢铁生锈的方法____.

(3)焊接钢件时要先除去其表面的锈垢,用稀硫酸除锈的化学方程式为____ .要检验除锈过程产生的废液中是否含有硫酸,可选择的试剂是____ (填字母).

A.酚酞    B.铁粉    C.氧化铜     D.氯化钠溶液.

上一题 下一题 0.0难度 选择题 更新时间:2016-10-09 05:37:28

答案(点此获取答案解析)

C,\u6c34\u3001\u6c27\u6c14,\u5237\u6f06\uff08\u5408\u7406\u5373\u53ef\uff09,3H2SO4+Fe2O3<\

同类题3

阅读下面短文,掌握其大意,然后从各题所给出的A、B、C和D项中,故答案选出最佳选项。

    When I was a young boy, my family was very poor. I would often help do something for the neighbors to 1 a little pocket money.

    One day I 2 on the door of an elderly woman and asked 3 she needed me to clean the yard. She asked why I was not in 4 and I showed her my worn 5, which no longer kept me warm. She 6 me to work in the yard. When I finished, she looked at me and said, “I suppose you want to be 7 now.” She then 8 a jar filled with dollar bills and said, “I'm glad you've done a 9 job today but that is not something you should be doing again. I want you to 10 new clothes and get back to school. I also want you to come back to 11 me with your report card and I will 12 you when I see you have worked hard and have some good 13. Now reach out your little hands and take out as much 14 as you can.”

    I put my hands in the jar and 15 so much money that it was 16 for me to buy what I badly needed. Later, I returned several times to see the woman and she did just as she 17. She looked at my report card and gave me a handful of dollars and some delicious food every time I 18 her that I had an “A”.

    I was twelve years old when I moved from that neighborhood. I will never forget the huge 19 this wonderful lady made over my life with her 20. This is something I hope to do myself in this lifetime over and over again.