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。

    In much of Asia, especially the so-called “rice bowl” cultures of China, Japan, Korea, ____Vietnam, food is usually eaten with chopsticks.

    Chopsticks are usually two long, thin pieces of wood or bamboo. They can also be made of plastic, animal bone or metal. Sometimes chopsticks are quite artistic. Truly elegant chopsticks might ____ (make) of gold and silver with Chinese characters. Skilled workers also combine various hardwoods and metal ____ (create) special designs.

    The Chinese have used chopsticks for five thousand years. People probably cooked their food in large pots, ____ (use) twigs（树枝）to remove it. Over time, ____ the population grew, people began cutting food into small pieces so it would cook more quickly. Food in small pieces could be eaten easily with twigs which ____(gradual) turned into chopsticks.

    Some people think that the great Chinese scholar Confucius, ____ lived from roughly 551 to 479 B.C., influenced the ____ (develop) of chopsticks. Confucius believed knives would remind people of killings and ____ (be) too violent for use at the table.

    Chopsticks are not used everywhere in Asia. In India, for example, most people traditionally eat ____ their hands.

化简与求值：

（1）化简：$\frac{1+\tan 15°}{1-\tan 15°}$；

（2）已知α，β都是锐角，cosα=$\frac{1}{7}$，cos（α+β）=﹣$\frac{11}{14}$，求cosβ的值．

当我们从学习中逐渐____的时候，当我们的____在学习中获得满足的时候，当我们通过学习发现

____的时候，学习的快乐就洋溢在我们的心中。

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