阅读下面短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式。

    Malala Yousafzai, 19, is a Pakistani youth activist. She is the ____（young）person in the world ever to be named United Nations（U.N.）Messenger（信使）of Peace. The United Nations is ____ international organization, which is meant to encourage ____（country）to work together on different opinions without the use of war. Yousafzai has ____(glad) accepted the role of working for girls'education. Usually, a messenger ____(stay) in the position（职位）for three years. “If ____ want to see your future bright, you have to start working now and not wait ____ anyone else,” she said at the acceptance meeting in New York. In 2012, Yousafzai was nearly killed by the Taliban because she worked hard ____(get) the same education for young girls in Pakistan. But later her condition improved. ____ a brave girl! Since then Yousafzai ____(become) a symbol for peace and girls' right to receive an education.

①DNA位于染色体上     ②DNA是染色体的主要成分    ③每条染色体上通常含有1个DNA分子   ④染色体和DNA都是遗传物质   ⑤染色体就是DNA

先化简，再求值：4x•x+（2x﹣1）（1﹣2x）．其中x= $\frac{1}{40}$ ．

综合性学习。

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