下列最稳定的自由基是()。 A.A B.B C.C D.D

题型:单项选择题

问题:

下列最稳定的自由基是()。

A.A

B.B

C.C

D.D

考点:机动车维修技术有机化学基础知识有机化学基础知识题库
题型:单项选择题

阅读理解。

  A 50-year-old American officer (官员) came back to his school. The

teacher asked him to give a talk to the small boys and girls there. The talk was

about the love of' their great country. All the little   ones were sitting in a large

meeting-room. The old officer went up and began speaking. He said, " boys and

girls,  I studied in this school forty years ago. When I was your age, we were not

as happy as you are today. Think about it and answer me, why are you so happy

now?"

  No sound came from the children. The old man waited for a long time. Then

a short boy in the front put up his small dirty hand. "Good boy! Please answer

me, dear. " said the officer.

  With a big smile on his face, the boy stood up and said, "if you speak long

enough, we won't have math and  biology  (生物学) lessons this morning. "

1. The old man came back to school _____.

A. to listen to a talk       

B. to have lessons

C. to give a talk          

D. to see his children

2. The officer studied in this school when he was _____

A. fifty                      

B. ten

C. twenty                    

D. children

3. The children were _____ before.

A. as good as              

B. as well as

C. as happy as            

D. much happier than

4. The short boy in the front _____.

A. didn't understand the question and answer it

B. told the truth

C. wanted to make others laugh

D. wanted to make the officer angry

5. After reading the last part of' the story, we know that _____.

A. the short boy liked the talk very much

B. all the children liked the talk

C. the short boy didn't like studying his lessons

D. some of' the children liked to listen to a funny story

题型:单项选择题

B细胞特有的表面标志()。

A.CD4

B.CD8

C.CD20

D.CD3

E.CD19

题型:单项选择题

与类风湿关节炎的发病有关的是()

A.变形杆菌

B.EB病毒

C.HLA-DR4

D.HLA-B27

E.雌/雄激素失调

题型:单项选择题

化学消毒灭菌法的作用机制是什么?

题型:单项选择题

某水利施工企业2014年12月12日取得水利安全生产标准化一级达标证书,若该企业希望在证书有效期满前申请将水利安全生产标准化一级达标证书延期三年,则需满足以下哪些条件()。

A.2015、2016、2017年均完成年度自评

B.持续改进安全生产标准化工作

C.2017年9月12日至12月12日之间向水利部提出延期申请

D.由评审机构复评、水利部审定

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