问题 单项选择题 A1/A2型题

IgG分子用木瓜蛋白酶水解后可分解为()

A.F(aB.2+Fc

B.Fab+2Fc

C.2Fab+Fc

D.2Fab+2Fc

E.F(aB.'2+Fc'

答案

参考答案:C

解析:IgG用木瓜蛋白酶水解后可分解为3个片段,其中2个完全相同的片段,具有结合抗原的能力,称为抗原结合片段(Fab段);另1个片段在低温和低离子强度下可形成结晶,称为可结晶片段(Fc段)。

选择题
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There are some very good things about open education .This way of teaching allows students to grow as people ,and to develop their own interests in many subjects .Open education allows students to be responsible for (负责)their  own education, as they are responsible for what they do in life .Some students do badly in traditional classrooms. The open classroom may allow them to   enjoy learning .Some students will be happier in an open education school .  They will not have to worry about grades or rules .For students who worry   about these things a lot, it is a good idea to be in an open classroom.  

But many students will not do well in an open classroom. For some students ,there are too few rules .These students will do little in school. They will not make good use of open education. Because open education is so different from traditional education, these students may have a problem of getting used to making so many choices. For many students it is important to have some rules in the classroom. They worry about the rules even when there are no rules .Even a few rules will help this kind of students. The last point about open  education is that some traditional teachers do not like it .Many teachers do not believe in open education. Teachers who want to have an open classroom may have many problems at their school.

You now know what open education is .Some of its good points and bad points have been explained .You may have your own opinion about open education. The writer thinks that open education is a good idea, but only in theory. In actual fact, it may not work very well in a real class or school. The writer believes that most students, but of course not all students, want some structure in their classes. They want and need to have rules. In some cases, they must be made to study some subjects .Many students are pleased to find subjects they have to study interesting. They would not study those subjects if they did not have to.

小题1:Open education allows students to         .

A.grow as they are educated

B.be responsible for their future

C.develop their own interests

D.discover subjects outside class小题2:Some students like open education but some students will do little in an open classroom because      .

A.there are too few rules

B.they hate activities

C.open education is similar to traditional education

D.they worry about the rules小题3:Which of the following is Not mentioned in the passage?

A.Some traditional teachers do not like open education.

B.Many teachers do not believe in open education.

C.Teachers may have problems in open classroom.

D.The teachers’ feelings and attitudes are important to the students.小题4:Which of the following can best summarize(总结)the passage?

A.Open education is a really complicated idea.

B.Open education is better than traditional education.

C.Teachers dislike open education.

D.Open education is a good idea in practice.