Why did they lower their heads in shame according to the passage?
A. They did not dare to answer.
B. They had mistaken the relationship of the mice.
C. They regretted driving a poor blind mouse away.
D. They did not express themselves much better.
第1题:
DID(Drug InduCedDiseases)( )。
第2题:
第3题:
已知Sid商店,Pid商品编号,Cid商品名称,Did经营部,Mgr经营部经理,Scale经营部规模。下列属于3NF的关系模式是_________。
A.R(Sid,Pid,Cid,Did,Mgr,Scale)
B.R(Sid,Pid,Did)
C.R(Sid,Pid,Cid,Did )
D.R(Sid,Pid,Did,Scale)
第4题:
( )
A.do
B.doing
C.to do
D.did
第5题:
16、已知Sid商店,Pid商品编号,Cid商品名称,Did经营部,Mgr经营部经理,Scale经营部规模。下列属于3NF的关系模式是_________。
A.R(Sid,Pid,Cid,Did,Mgr,Scale)
B.R(Sid,Pid,Did)
C.R(Sid,Pid,Cid,Did )
D.R(Sid,Pid,Did,Scale)
第6题:
在任何情况下,经典的DID模型和控制个体效应的DID模型估计得到的结果是一样的。