DNA聚合酶有两种方式保证复制的准确性，即选择性添加正确的核苷酸和移除错配的核苷酸。某些突变的DNA聚合酶（突变酶）比正常DNA聚合酶催化的精确度更高。下列有关叙述正确的是（）

题干

A：突变酶中的氨基酸序列没有发生改变

B：突变酶作用的底物是四种核糖核苷酸

C：突变酶极大地提高了DNA复制的速度

D：突变酶降低了基因突变频率不利于进化

上一题下一题 0.0难度选择题更新时间:2017-10-11 07:04:37

D

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Interesting festivals in the world

	Throwing tomatoes﹣Spain（西班牙） Spain takes "tomatoes fights" to a whole new level. But the tomatoes are being thrown, not eaten. The festival takes place during the last Wednesday in August. Trucks（卡车）carry tomatoes into the square. People rush to the tomatoes and throw them into the crowd.
	Rolling cheese﹣England This festival is celebrated on the last Monday in May. It takes place on Cooper's Hill. A large wheel of cheese（奶酪）is rolled down Cooper's Hill. The festival is actually a race where people run down the hill after the rolling cheese. The first person to cross the finish line at the bottom of the hill wins the cheese.
	Burning man﹣The United States The Burning Man Festival lasts a week, it is from the Monday before labor Day to Labor Day（which falls on the first Monday in September in America）. The festival takes place in the Black Rock Desert. The best part of the festival is the burning of a large sculpture of a man.
	Pouring water﹣Thailand The Songkran Festival is the celebration of the New Year in Thailand. Rather than a single day. Thailand celebrates the New Year from April 13th to April 15th. Thai people run after each other pouring water. Songkran is one of the most important reasons why foreigners travel to the beautiful land.