问题
问答题
（1）为什么有的铁制品如水龙头等要镀铬？如果镀金怎么样？
（2）铜钱在历史上曾经是一种广泛流通的货币，已知铜的熔点是1183.4℃，铁的熔点是1534.8℃。试从物理性质或化学性质的角度分析为什么用铜而不用铸造货币。
答案
（1）水龙头镀铬耐磨、耐腐蚀，水龙头镀金价格贵、易磨损
（2）铜的熔点比铁低，易于铸造；铁比铜活泼，容易锈蚀
搜题请搜索小程序“爱下问搜题”
（1）为什么有的铁制品如水龙头等要镀铬？如果镀金怎么样？
（2）铜钱在历史上曾经是一种广泛流通的货币，已知铜的熔点是1183.4℃，铁的熔点是1534.8℃。试从物理性质或化学性质的角度分析为什么用铜而不用铸造货币。
（1）水龙头镀铬耐磨、耐腐蚀，水龙头镀金价格贵、易磨损
（2）铜的熔点比铁低，易于铸造；铁比铜活泼，容易锈蚀
用方框中所给单词的适当形式填空，使短文通顺、正确、连贯（每个单词限用一次）。
To get the help you need, think about ___小题2:_____ to family and friends, others who also have trouble, people you meet in support groups and even help ____小题3:______. No one needs to face big trouble alone. When people in trouble look for and receive help from others , they often find it___小题4:____ to live through. You may find it hard to ask for or accept help. After all, you are used to taking care of yourself. Maybe you think that asking for help shows___小题5:_____. Or perhaps you do not want to let others know that some things are hard for you to do. All these feelings are not___小题6:_____. As one man with a great difficulty once said:“I had always been the strong one. Now I had to turn to others for help. It wasn’t easy at first,____小题7:_____ the support of others helped me get through a lot of hard times.” People feel good when they help others. Your friends may not know what to say or ___小题8:____to act when they are with you. Some people may even avoid you. But they may feel better when you ask them to cook a meal or pick up__小题9:____ child after school. There are many ways that family, friends, other people who have similar troubles and many others can help. ___小题10:____ turn, there are also ways you can help and support them! |