Which of the following can be inferred about Michael Phelps from the article?
A. He wasn't a talented swimmer as a child,but he worked hard to improve.
B. He has never be enable to pick himself backup after major setbacks.
C. He is not satisfied with average performance and instead strives to be outstanding.
D. He is someone who gets discouraged easily and would rather take the easy way out.
查看答案
What does the author want to convey through the passage?
A. To encourage people to have persistent and never-say-die spirit
B. To tell people that innate ability is the shortcut to success
C. To tell people that genius doesn't need to work hard
D. To tell people that great people also have failures
贵州除了汉族以外，共有苗、布依、侗、土家等（）个世居少数民族。
在历史发展过程中，影响贵州民族文化的族系有华夏族系、氐羌族系、（）和百越族系。
市售的KMnO4常含有少量杂质，因此不能用精确称量的KMnO4来直接配制准确浓度的溶液，常用无水草酸钠作基准物来标定溶液的浓度。在标定过程中，需控制温度、酸度、滴定速度。试回答下列问题：（1）能否用盐酸代替硫酸？为什么？（2）写出无水草酸钠标定高锰酸钾溶液的离子反应方程式。（3）选用何种指示剂？滴定终点时什么现象？（4）温度过高对结果有何影响？开始滴定速率过快又有何影响？（选择“偏高”、“偏低”、“无影响”）
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