A:28
B:32
C:33
D:27
—Simon, how old is your father this year?
—______. And we just had a special birthday party for his _____ birthday last Sunday.
已知点A(k,4)在双曲线y=−4x上,则k的值是( )
命题“∃x∈R,使得x2+x+1<0”的否定是 ( )