1954年，____（会议）制定了《中华人民共和国宪法》，这是我国第一部____ 类型的宪法。

$($ 参考数据： $\text{sin}{71}^{\circ }\approx 0.95$ ， $\text{cos}{71}^{\circ }\approx 0.33$ ， $\text{tan}{71}^{\circ }\approx 2.90)$

【查阅资料】1. MgCO₃·nH₂O微溶于水；2. MgCO₃·nH₂O在230℃时开始失去结晶水， 400℃以上时开始分解生成三种氧化物。

I．合成碳酸镁晶须

步骤：①配制一定溶度的MgSO₄溶液和NH₄HCO₃溶液；②量取一定量的NH₄HCO₃溶液于容器中，搅拌并逐滴加入MgSO₄溶液，控制温度50℃，反应一段时间；③用氨水调节溶液pH至9.5，放置1h后，过滤、洗涤、干燥得碳酸镁晶须产品。

    Children today have many things to play with. They can watch television, surf ____ Internet, or play video games. But what do you think children ____ (do) for fun long ago? They read books.

    Some of you might ask, "Are books ____ (real) fun?" Believe it or not, books provide many things that television or computers cannot. Since books use only words ____ (tell) a story, they can improve your imagination. You can picture the characters and background in your head and you can also imagine ____ the characters feel.

    The words and sentences that are used in storytelling are also very interesting and usually cannot be found often on television or on websites. They are sometimes so beautiful and touching ____ they can bring tears to your eyes.

    Books also help us to think harder and ____ (deep). As we continue ____(read), we ask questions to ____(our) and try to find answers.

    These are some of the ____(reason) why books are so fun to read.

    Remember: the more you read, the more you grow.

下列各组图形不一定相似的是（　　）