问题
选择题
下列变化中，必须加入氧化剂的是（ ）
A．CuO→Cu
B．CO2→CO
C．O2→H2O
D．Cl-→Cl2
答案
题中A、B、C中Cu、C、O元素化合价分别降低，应加入还原剂，D中Cl元素化合价升高，被氧化，应加入氧化剂，
故选D．
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下列变化中，必须加入氧化剂的是（ ）
A．CuO→Cu
B．CO2→CO
C．O2→H2O
D．Cl-→Cl2
题中A、B、C中Cu、C、O元素化合价分别降低，应加入还原剂，D中Cl元素化合价升高，被氧化，应加入氧化剂，
故选D．
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| When I was young, I belonged to a club that did community service work.There was one specific event that was unusual for me.I spent three or four hours handin  g out warm dinner to the homeless outin the streets.After that I went to a homeless shelter not far from the Bay Bridge. I was in high school and at the time my sister was too young to__1__.She wanted to help, __2__ she made four or five dozen chocolate chip cookies for me to__3__and hand out to people.When getting to the homeless shelter__4__passed out the re  maining meals.__5__, I began making sandwiches and__6__them with the crowd.I had the containers with my__7__cookies in them and began to__8__, offering them to anyone near me. I__9__an old gentleman and said, "Sir, would you like a cookie?" He stopped and turned around, __10__and said, "What did you say?Did you call me sir?" I told him I __11__, and his eyes__12__a little bit and he said, "No one has__13__called me sir." So he__14__. It struck me. I explained I had been raised that__15__color and social status, everyone deserved respect.It __16__me to think that just because he was homeless, no one__17__him the honor.It broke my heart, and I__18__I just didn't understand__19__no one ever called him sir?I had never thought that anyone was below me because I wasn't raised that way.Every__20__person deserves to be treated with dignity. Years later, I still carry that memory and the lessons it taught me.Sometimes, what we take for granted can really make a difference in someone's life. How have you made a difference to others?How have others made a difference to you? | ||||
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