根据下面所给的AAA数据库，按照下列每种功能写出相应的Transact-SQL语句或程序段 假设使用名称为AAA的数据库，它包括Students（学号char（8），姓名varchar（8），年龄int，专业varchar（20），入学日期DateTime）和Score（学号char（8），课程名varchar（10），成绩numeric（5，2））两张表。显示出Students表中所有学生记录的学号列的前四个字符。
第1题：
根据下列句子的意思及所给的汉语提示，写出空缺处单词、固定短语或固定搭配的正确形式。
81. This is our _____________________ (三) time to plant trees.
第2题：
参考答案：Television has both advantages and disadvantages to us.On the one hand, it can make us informed of daily news, let us know the outside world, provide lessons for the learners, and can even bring joy toour lives as well.
On the other hand, some television programs have been extremely harmful to the young.A case in point is the movies with violent scenes.Watching TV too long can do harm to our body and it’s a great distraction for us to work.
So young people should learn to get ride of the bad influences of TV and learn to make use of the advantages that TV can bring us.
第3题：
A.aaa.txt
B.aaa.wav
C.aaa.doc
D.aaa.bmp
第4题：
试写出图题6-4所示电路的驱动方程、状态方程、输出方程与状态图，并按
照所给波形画出输出端Y的波形。
由于状态方程=输出方程与左图一样，因此具有与左图相同的状态表、状态图与时序图。第5题：
第6题：
参考答案：Internet plays an important role in our life.First, The world gets smaller and communication becomes easier and faster, because through the Internet we can get to know people from all over the world.Besides, we can work at home by sending email and accessing online information.Finally, online shopping makes our life more convenient.But as many other modern inventions, Internet has its problems.For instance, there is too much junk information on the net, and it wastes our time.Even worse, some evil persons commit crimes using the Internet technology.Thousands of people have fallen in love with the Internet.It’s necessary to adopt stricter administration measures so that it will serve us better.
第7题：
写出每种关系模式的主键。
第8题：
抄写下面的句子，并根据拼音写出相应的汉字。（2分）
仰望天穹，让心飞上云duān。
第9题：
请写出一条修改数据库定义的语句，将AAA数据库的初始大小更改为5MB，最大空间限定为10MB。
第10题：
用汉语拼音写出下列汉字所代表的音节，并从结构角度给韵母分类。（写出基本音节即可，不要求标注声调。） ①光 ②辉 ③照 ④耀 ⑤你