唾液腺、垂体、甲状腺都属于内分泌腺，无导管，分泌物直接进入血液。

    Shenzhen is a city in South China．It is not very big, but it has attracted people of the whole country and the whole world as well．

    Just about thirty years ago, it was only a small fishing village．There were not many people there． Most of them lived on fishing．Things have greatly changed since the 1980s．It became the first special economic zone(经济特区) in China．

    Because of the opening policy(政策), economic changes between China and the outside world have increased greatly．People can come and go easily between Shenzhen and Hong Kong．Both foreigners and Chinese have built a lot of factories, companies and tourists' attractions there．People all over the country have come to find jobs．Many of them have settled down in this new booming(兴起的) city．

    Shenzhen has been developing so fast that it has become a well－known metropolis(大都市) in China．

该小组同学利用如图装置进行实验．

①对试管内的绿色固体进行加热，至完全分解，观察到A装置中绿色固体逐渐变成黑色，B装置中无水硫酸铜变成蓝色，C装置中澄清石灰水变浑浊．

②取少量加热后生成的黑色固体于试管中，加入稀硫酸．观察到黑色固体逐渐溶解，溶液变成蓝色．

③取少量上述蓝色溶液加入试管中，浸入一根洁净的铁丝．观察到铁丝表面有红色物质析出．

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