题干

铁是人体必须的微量元素,菠菜因富含铁元素(化合态)而成为补铁的食物之一。小明设计实验探究菠菜中含有Fe2还是Fe3

首先,他查阅了相关资料,得到以下信息:

①在少量含Fe3的溶液中加入硫氰化钾(KSCN)溶液,溶液变为血红色;

②在少量含Fe2的溶液中加入酸性高锰酸钾溶液,酸性高锰酸钾溶液紫色褪去;

然后,小明设计并动手做实验,实验步骤如下:

步骤一:

步骤二:分别取2 mL溶液B于三支试管中,实验操作和现象如表所示:

试管

加入适量检验药品

实验现象

酸性高锰酸钾溶液

酸性高锰酸钾溶液紫色褪去

硫氰化钾溶液

溶液不变红色

先加入稀硝酸,再加入硫氰化钾溶液

溶液变红色

请回答下列问题:

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    The United States is a country of immigrants. It is a place where people from all over the world come to build a better life. Some immigrants bring their families. Some bring a few of their favorite things. Others come alone with nothing but determination. One thing that every immigrant brings with them is their culture.

    American immigration began in 1607 with the colony (殖民地) of Jamestown. In 1620, another group of people left England to build a settlement in America. They wanted to go to a place where they could practice their religion freely. Then many more people left their homes in Europe to build a better life in America. Many also came to America from Africa. By 1770, more than two million people had moved to America. Later on, more people came to the United States than ever before.

    In cities all over America, you can see different cultures that formed this country. Many things that you may think of as being “American” are actually from a foreign culture. Some of the best examples of this are the foods people eat. Pizza and spaghetti are foods that all Americans know and love. But both of them are from Italy. Baseball is an all-American sport. But the hot dogs that people eat during the game are a type of food that was brought to America by German immigrants.

    Over time, pizza and hot dogs have become a part of what is considered to be American food. In the same way, different groups of people have come together to define what an American is. An American can be a person of any background. An American can be of any faith. An American can be of any skin color. They can speak English clearly. They can speak English with an accent. Each new immigrant adds something new to American culture. It will keep changing as more people come to this country.