为用户与数据库系统提供接口的语言是( )。
A．高级语言
B．数据描述语言(DD
C．数据操纵语言(DM
D．汇编语言
参考答案：C
The old man sat in front of the television every evening, happy______ anything that happened to be on.
A．to watch
B．watching
C．watched
D．to have watched
某导体的电阻是2Ω，当通过1A电流时，导体的功率是__________W。通电1min时,导体上产生的热量是__________ J。
