问题 单项选择题 A1/A2型题

核酸中核苷酸之间的连接方式是()。

A.C-N糖苷键

B.2’,5’-磷酸二酯键

C.3’,5’-磷酸二酯键

D.肽键

E.α-1,6-糖苷键

答案

参考答案:C

解析:核酸分子中各核苷酸之间的连接都是由前一个核苷酸的3’-羟基和后一个分子的5’-磷酸缩合形成3’,5’-磷酸二酯键。

单项选择题
写作题

     When I was a child, my parents sent me to a special class to learn calligraphy(书法) . They kept

asking me to practice it because they believe mastering the art of calligraphy can help me produce

beautiful handwriting. Later on in primary school and junior high school, we hand in one whole page of

calligraphic exercise per week. At that time, calligraphy was considered an important skill that children

have to learn.  

     Today along with the popularity of computers, writing is increasingly done by punching in on the

keyboard instead of holding any kind- of real pens. Teachers and parents value computer knowledge

much more than the art of calligraphy. As a result, people care less andless about calligraphy, which has

now become no more than a simple hobby enjoyed by only a few people.It is very sad to witness the

death of such a wonderful tradition.

【写作内容】

1.以约30词概括短文的要点;

2.然后以约120个词就,并包括如下要点:

      ①你曾经学过书法吗?周围有没有人学习?          

      ②简述你的理由。

【写作要求】

1.可以使用实例或其他论述方法支持你的论点,也可以参照阅读材料的内容,但不得直接引用原文中的句子;

2.标题自定。