开展对学生进行安全防范意识教育的演练（     ）

    For many in the United States, Arab-Americans are an invisible part of the population. Though Arab-Americans as a community have made great contributions to American society in fields from literature to politics to medicine, many Americans know very little about Americans of Arab backgrounds.
    Arab history in the United States goes back to the late 1800’s when large numbers of Arab immigrants first began making their journey to a land known simply as “Amreeka”.
    Historians generally describe Arab immigration to America in two waves. The first wave took place between 1860 and 1924.The first wave consisted of Lebanese and Syrian, and some Egyptian immigrants. These new immigrants, who were mostly Christian, came to America in search of better opportunities. Even the doomed Titanic, which set sail for America in 1912,had close to a hundred Arab passengers aboard. The majority of Arab-Americans today are descendents of the first wave of immigrants; they are the third or more generation Americans.
The second wave of immigrants followed after World War Ⅱ,caused by political unrest in the Middle East. This second wave of immigrants consists of mainly Arab Muslims（穆斯林）and continues to this day.
    Arab-Americans make up 3 million of the population in the United States, according to demographers. And quite different from popular belief, 64 percent of them are American-born. Eighty-two percent of Arab-Americans are US citizens.
Arab-Americans are beyond the national average in both education and income. Education is important among Arab-Americans; 82 percent have high school diplomas, 36 percent have bachelor's degrees or higher, and 15 percent have graduate degrees. The-median（中位数的）average income among Arab-Americans is $39,580, which is higher than the US average.

背景材料：2016年8月22日，在举世瞩目的第三十一届奥林匹克运动会上，中国女排以3﹣1战胜塞尔维亚女排，中国女排时隔12年再夺奥运冠军，创造了奇迹。比赛后郎平说，女排精神不是赢得冠军，而是有时候知道不会赢，也竭尽全力。是你一路虽走得摇摇晃晃，但站起来抖抖身上的尘土，依旧眼中坚定。女排夺冠极大振奋了国民精神，掀起学习“女排精神”的新热潮。

按课文填空。

自选商场

自选商场里的东西真多。

我和妈妈从货架上选了一些食品。收款的阿姨用电脑很快算出了要付的钱。

在自选商场买东西真方便。