设有关系R(A,B,C,D,E),A、B、C、D、E都不可再分,则R一定属于A) 1

题型:单项选择题

问题:

设有关系R(A,B,C,D,E),A、B、C、D、E都不可再分,则R一定属于

A) 1NF
B) 2NF
C) 3NF
D) 以上3个选项都有可能

考点:计算机等级考试数据库技术三级数据库技术笔试
题型:单项选择题

1927年,国民党政府把各省、市、县的警察机关改为( )

A.“公安局”

B.“警察局”

C.“保安局”

D.“巡警局”

题型:单项选择题

GUATEMALA CITY (Reuters) – A fish that lives in mangrove swamps(红树沼泽)across the Americas can live out of water for months at a time, similar to how animals adapted(适应)to land millions of years ago, a new study shows.

The Magrove Rivulus, a type of small killifish, lives in small pools of water in a certain type of empty nut or even old beer cans in the mangrove swamps of Belize, the United States and Brazil. When their living place dries up, they live on the land in logs(圆木),said Scott Taylor, a researcher at the Brevard Endangered Lands Program in Florida.  

The fish, whose scientific name is Rivulus marmoratus, can grow as large as three inches. They group together in logs and breathe air through their skin until they can find water again. 

The new scientific discovery came after a trip to Belize.  “We kicked over a log and the fish just came crowding out,” Taylor told Reuters in neighboring Guatgemala by telephone. He said he will make his study on the fish known to the public in an American magazine early next year. 

In lab tests, Taylor said he found the fish can live up to 66 days out of water without eating. 

Some other fish can live out of water for a short period of time. The walking catfish found in Southeast Asia can stay on land for hours at time, while lungfish found in Australia, Africa and South America can live out of water, but only in an inactive state. But no other known fish can be out of water as long as the Mangrove Rivulus and remain active, according to Patricia Wright, a biologist at Canada’s University of Guelph. 

Further studies of the fish may tell how animals changed over time. 

“These animals live in conditions similar to those that existed millions of years ago, when animals began making the transition(过渡)from water onto land,” Wright said.  

小题1:The Mangrove Rivulus is a type of fish that _______. 

A.likes eating nuts

B.prefers living in dry places

C.is the longest living fish on earth

D.can stay alive for two months out of water小题2:Who will write up a report on Mangrove Rivulus?

A.Patricia Wright

B.Researchers in Guatemala

C.Scientists from Belize

D.Scott Taylor小题3:According to the text, lungfish can________

A.breathe through its skin

B.move freely on dry land

C.remain alive out of water

D.be as active on land as in water小题4:What can we say about the discovery of Mangrove Rivulus?

A.It was made quite by accident

B.It was based on a lab test of sea life

C.It was supported by an American magazine

D.It was helped by Patricia Wright

题型:单项选择题

金融衍生产品的主要功能是风险管理,所以其自身的风险是较低的。( )

题型:单项选择题

下列关于期货交易风险揭示和管理的表述,错误的是()。

A.期货公司应当在传递交易指令前对客户账户资金和持仓进行验证

B.期货公司为客户提供互联网委托服务的,应当对客户进行互联网交易风险特别提示

C.《期货交易风险说明书》由期货公司自行制定

D.期货公司在为客户开立账户前,应当向客户出示《期货交易风险说明书》

题型:单项选择题

下列关于文档文件附件的描述,错误的是:()

A.附加的文件以链接的形式存在,并没有包含到PDF文档中

B.符合PDF/X-1a规范的PDF档不允许添加文档附件

C.可为通过“文档(Document)>附加文件(Attach a File)”命令,为附加的文件指定一个外观图标及图标颜色

D.文件附件可通过“高级(Advanced)>PDF优化器(PDF Optimizer)”来全部删除掉

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