设f表示某个二元逻辑运算符,PfQ的真值表如表1-10所示,则PfQ等价于()
表1-10真值表
A.
B.
C.
D.
参考答案:B
解析:
根据真值表,可以检验得到B正确。
Watching the online open courses of some famous European and American universities _______a new fashion among white collars in China over the past few months.
A.became
B.had become
C.has become
D.becomes
当送电线路、变电所因海拔高度引起气象条件变化而异于标准状态时,可按照相关规定校正。海拔高度1000m及以下地区,按海拔高度( )条件校正。
A.0m; B.100m; C.500m; D.1000m。