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问题 问答题

现取石灰石样品12g，加入50g稀盐酸恰好完全反应（假设杂质不溶于水且不与酸反应），最后称得剩余物的总质量为57.6g．计算：

（1）放出二氧化碳多少g？

（2） 石灰石中碳酸钙的质量分数．

答案

（1）根据质量守恒定律，放出二氧化碳的质量=12g+50g-57.6g=4.4g；

（2）设参与反应的碳酸钙的质量为x，

CaCO3+2HCl=CaCl2+H2O+CO2↑

100                 44

x                   4.4g

∴

100
44
=
x
4.4g
，

解之得：x=10g；

石灰石中碳酸钙的质量分数为：

10g
12g
×100%≈83.3%．

答：（1）放出二氧化碳4.4g；

（2）石灰石中碳酸钙的质量分数为83.3%．

完形填空

When I knocked into a stranger, “Oh, excuse me, please.” was my        . He said, “Please excuse me, too.” We were very       , this stranger and I. But at home a different story is told.

Later that day, while I was cooking the evening meal, my daughter stood beside me quietly. When I turned, I nearly made her fall onto the floor. “Get out of my way!” I said       . She walked away with tears(眼泪) in her eyes. I didn’t     how rudely I’d spoken. Later, I went into the        again, and found some flowers there by the door. Those were the flowers she picked for me. I felt really        and my tears began to fall. For a stranger, we can be polite, but for the ones we love, we seem to be rude.

If we die tomorrow, the company we are working for could easily take our place soon. _    the family we left behind will feel the loss(损失) for the rest of their lives.

      is behind the story? You know what is the full word of       ?

FAMILY = (F)ather    (A)nd    (M)other    (I)   (L)ove   (Y)ou

Fill life        love and courage, and we shall live an uncommon life.

小题1: 

A．report

B．reply

C．reason

D．review小题2: 

A．proud

B．rude

C．upset

D．polite小题3:

A．quietly

B．happily

C．angrily

D．deeply小题4:

A．check

B．ask

C．realize

D．mean小题5:

A．kitchen

B．living room

C．office

D．building小题6:

A．excited

B．lonely

C．disappointed

D．sorry小题7:

A．Because

B．But

C．Unless

D．Since小题8:

A．What

B．How

C．Why

D．Who小题9:

A．love

B．family

C．home

D．courage小题10:

A．of

B．for

C．with

D．from
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选择题

甲、乙两人进行乒乓球比赛，比赛规则为“3局2胜”，即以先赢2局者为胜．根据经验，每局比赛中甲获胜的概率为0．6，则本次比赛中甲以2:1的比分获胜的概率为（     ）

A．0．288

B．0．144

C．0．432

D．0．648
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