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问题 问答题

物质A是一种高熔点化合物，不溶于H2SO4、HNO3，却溶于HF，C是一种气体，D是白色沉淀，A、B、C、D之间的转化关系如图：

A是______  B是______

C是______  D是______．

答案

物质A是一种高熔点化合物，不溶于H2SO4、HNO3，却溶于HF，可以推断A为SiO2，由A

纯碱
高温
B+C，C是一种气体，考虑SiO2+Na2CO3
 高温 
.
 
Na2SiO3+CO2↑，B为Na2SiO3，C为CO2，B+C
H2O
D
△
A，D为H2SiO3（或H4SiO4），是白色沉淀，加热分解可以生成SiO2，符合转化关系，综合上述可知：

A为SiO2，B为Na2SiO3，C为CO2  D为H2SiO3 （或H4SiO4）；

故答案为：SiO2；Na2SiO3；CO2；H2SiO3 （或H4SiO4）．

听力题

单词拼写（共10小题；每小题1分，共10分）

小题1: In the old times, many political leaders were not thought ________（高度评价） of.

小题2:Father _______ (承诺，许诺)to buy me a computer if I do well in the final examination.

小题3: He is _______（诚实的） and he never tells lies.

小题4:Once he was the _______ （教练）of our football team

小题5:Many rare animals are in ________（危险）because they are being hunted for.

小题6:While reading, please pay much __________ （注意）to your pronunciation.

小题7:Our school was _________ （设计）by a famous professor from Tongji University.

小题8:People say that barking dogs don’t ________ .(咬)

小题9:Dave didn't __________ （回复）to any of her emails, which made her angry.

小题10:I am busy, so I have to e_________ （雇佣）a housekeeper to look after my children.
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问答题 简答题

在什么情况下梁箍筋的弯钩朝下？
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