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问题 单项选择题

下面所述技术： 　 　Ⅰ．索引技术 Ⅱ．时标（时间戳）技术 Ⅲ．封锁技术 　　那些是数据库管理系统的并发控制子系统通常采用的技术？

A． Ⅰ和Ⅱ

B． Ⅱ和Ⅲ

C． Ⅰ和Ⅲ 　　　

D． 都是

答案

参考答案：B

阅读理解

阅读理解。

     The Spring Festival is the Chinese New Year’s Day. It usually comes in February. Sometimes it comes in January. Everyone in China likes it very much.

     When it comes, Zhou Hua helps her mother clean their house, put up (张贴) the new pictures and do

some other housework. On that day, everybody in China often eats jiaozi (饺子) and New Year’s cake.

They can also enjoy some other delicious food. Zhou Hua likes New Year’s cake very much. But her

brother, Zhou Kun likes jiaozi better. They eat New Year’s cake and jiaozi in their house. How happy

they are!

1.The Spring Festival usually comes in ________.

A. February

B. January

C. March

D. December

2.________ helps Mum do some housework.

A. Zhou Hua

B. Dad

C. Zhou Kun

D. Zhou Hua and Zhou Kun

3.People often eat ________ on that day.

A. mooncakes

B. jiaozi

C. New Year’s cake

D. B and C

4.They often put up ________ during the Spring Festival.

A. beautiful coats

B. the old pictures

C. some photos

D. the new pictures

5.Zhou Kun likes ________ better.

A. New Year’s cake

B. cakes

C. jiaozi

D. food
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选择题

一钢瓶中储质量为m、密度为ρ的氧气，当住院病人用去的氧气后，瓶内剩余氧的密度是[ ]

A．ρ

B．

C．

D．3ρ

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