题干

同学们查阅资料,镁是一种化学性质非常活泼的金属,可以在多种气体中燃烧。同学们用下图所示装置分别进行镁条在二氧化碳和氮气中燃烧的实验。B中观察到镁冒出淡黄色的烟,并闻到刺激性气味。同学们对两个反应进行了探究。

 [查阅资料]

①氧化镁、碳酸镁均可以和盐酸反应。

②氮化镁(Mg3N2),淡黄色固体,无味,遇水产生白色沉淀氢氧化镁,并产生有刺激

性气味的氨气(NH3)。

实验1探究A中生成黑色固体和白烟的成分。

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symbol      different       blue     water      green       speed

because     connected      role      from      colors       for

    The meanings of colors play an important ____in our world. What a color pass to a person of the west, may be very ____to someone in the east. While a bride(新娘) may wear white to her wedding (婚礼) in Europe or America, a bride ____China may choose to wear a traditional red dress.

Here are some ____and what they represent (代表,象征) to various people of the world.

    RED

    In China red is a ____of luck and is used for many celebrations such as wedding and at the beginning of the New Year. In the United States red represents love and is used during Christmas and so on. Red is also represents ____and power in the west.

    BLUE

    People around the world think____and the sky with the color blue. For this reason, blue is widely ____with peace and calm. But to the Cherokees (切罗基族人), blue meant trouble or failure. In the United States we have come to connect the color blue with sadness.

    GREEN

    In Paris, all garage collectors are clothed in green, drive green trucks and the bins are also green. In many parts of the world,____ has become a symbol of kindness and the earth.

    YELLOW

    Yellow is a color that symbolizes the sun. In the United States, school buses and taxis are often yellow____they can catch the eyes. But to the Egyptians, yellow was a color of mourning (哀悼).