问题 填空题

当数据库的存储结构改变时,可相应修改 【5】 ,从而保持模式不变。

答案

参考答案:答案:模式/内模式映射

解析:

[分析]: 数据库在3级模式中提供了两级映射:外模式/模式映射和模式/内模式映射。
(1)当模式改变时,由数据库管理员对各个外模式/模式的映射做相应的修改,可以使外模式保持不变。从而应用程序也不必改变,保证了数据与程序的逻辑独立性。
(2)当数据库的存储结构改变时,由数据库管理员对模式/内模式映射做相应的改变,可以使模式不变,从而应用程序也不必改变,保证了数据与程序的物理独立性。

阅读理解

阅读理解。

     "Congratulations, Mr. Jones, it's a girl."

     Fatherhood is going to have a different meaning and brings forth a different answer from every man who

bears these words. Some feel proud when they receive the news, while others worry, wondering whether

they will be good fathers. Although there are some men who like children and may have had considerable

experience with them, others do not particularly care for children and spend little time with them. Many fathers

and mothers have been planning and looking forward to children for some time. For other couples, pregnancy

was an accident that both husband and wife have accepted willingly or unwillingly.

     Whatever the reaction to the birth of a child, it is obvious that the shift from the role of husband to that of

father is a difficult task. Yet, unfortunately, few attempts have been made to educate fathers in this

remobilization process. Although numerous books have been written about American mothers, only recently

has literature focused on the role of a father.

     It is argued by some writers that the transition to the father's role, although difficult, is not nearly as great

as the transition the wife must make to the mother's role. The mother's role seems to require complete

transformation in daily routine and highly innovative adaptation; on the other hand, the father's role is less

demanding and immediate. However, even though we mentioned the fact that growing number of women are

working outside the home, the father is still thought by many as the breadwinner in the household.

1. According to the author, being a father _____.

A. brings a feeling of excitement to males

B. has a different meaning for those who have daughters

C. makes some men feel proud and others uneasy

D. means nothing but more responsibilities

2. The transition to the mother's role requires that the wife _____.

A. change her lifestyle in a highly innovative way

B. make a complete change in her everyday life to deal with the new situation

C. stay at home to take care of the baby

D. help her husband in his remobilization process

3. Some writers argue that with respect to the change of roles, fathers, compared with mothers, _____.

A. have to shoulder more burdens

B. have to make more difficult adaptations

C. have an easier job to do

D. can usually do a better job

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