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3、常见放热反应:⑴燃烧反应 ⑵活泼金属+酸或水→H2 ⑶中和反应 ⑷CaO +H2O

⑸一般化合反应是放热反应。

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2、常见吸热反应:⑴Ba(OH)2·8H2O+NH4Cl,⑵C+CO2或H2O(g),⑶一般分解反应都是吸热反应,⑷电离,⑸水解等。

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化学反应都有新物质生成,同时伴有能量的变化,据此可把反应分为:

1、放热反应:             。 吸热反应:              

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214. The lady said she would buy a gift for her daughter with the 

    .

A. 20 dollars remained      B. 20 dollars to remain

C. remained 20 dollars      D. remaining 20 dollars

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213. -Mum, why do you always make me eat an egg every day?

-      enough protein and nutrition as you are growing up.

   A. Get                B. Getting 

   C. To get               D. To be getting

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212. There are five pairs     , but I'm at a loss which to buy.

  A. to be chosen           B. to choose from

  C. to choose              D. for choosing

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211. -Let me tell you something about the journalists.

   -Don't you remember      me the story yesterday?

  A. told               B. telling 

  C. to tell             D. to have told

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210. When I got back home I saw a message pinned to the door,    “Sorry to miss you; will call later."

A. read      B. reads    C. to read    D. reading

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209. The purpose of new technologies is to make life easier,      it more difficult.

  A. not make            B. not to make  

  C. not making           D. do not make

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208. Robert is said      abroad, but I don't know what country he studied in.

  A. to have studied         B. to study      

  C. to be studying          D. to have been studying

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