【名词&注释】
亚硝酸钠(sodium nitrite)、新时代(new era)、化合价(valence)、多年来(many years)、有没有
[单选题]亚硝酸钠（NaNO2）是一种工业用盐，外观酷似食盐，人若误食，会引起中毒。亚硝酸钠中氮元素的化合价是（ ）
A. +1
B. +3
C. +4
D. +5
查看答案&解析
举一反三：
[单选题]DWhen I was twelve years old, my family were the first black people to move into an all white part of Grand Rapids, Michigan. Many of our new neighbors weren’t very welcoming. Some of them said angrily that we should return to where we came from. The children sometimes threw stones at me or drove me home from school.
A. Most of my teachers simply took no notice of me, but not Dorothy Bean, my history teacher. Miss Bean was angry at how badly I was being treated, but she didn’t say this to me. Miss Bean showed her respect for me by teaching me just like anyone else. Instead of being unnoticed, I was given a chance to show that I was clever. Miss Bean was the first teacher who ever made me think for myself. She always wanted to know what I thought about difficult questions. Was Thomas Jefferson right to buy Louisiana from France? Why? She expected me to have my own idea. Miss Bean was teaching me that thinking for oneself was the real key to education.
B. One day, when I was not paying attention in class, Miss Bean suddenly threw an eraser at me. The eraser hit me right on the hand and sent my pencil flying. The whole class were very surprised at first, then started laughing. This event became famous in the school and, because it happened to me, the students wanted to get to know me. So that’s the story of how Dorothy Bean made me her target（靶子）, and how I became just another kid in school.
C. 51. The author and his family were not welcomed by the local people because ________.
D. they returned from another country
E. they had different skin colour
F. they spoke a different language
G. they moved to a wrong place
[单选题]下列句子没有语病的一项是（2分）
A. 有没有正确的环保观， 低碳生活能否实现的关键。
B. 开展“无烟日”活动，可以增强人们的自我健康保护。
C. 我们在心里由衷地感谢老师多年来的默默付出。
D. 新时代的教育应该培养学生善于观察、善于思考、善于创造的水平。
[单选题]如果一个数的平方与这个数的差等于0，那么这个数只能是（ ）
A. 0 B.－1
B. 1
C. 0或1
[单选题]9．I think doing the dishes _________ ．
A. are boring
B. are bored
C. is boring
D. is bored
[单选题]Theplane______whenwegottotheairport.
A. hadtakenoff
B. wastakenoff
C. willtakeoff
D. istakingoff
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