已知点A(1,﹣2),B(5,6)到直线l:ax+y+1=0的距离相等,则实数a的值等于C [ ]
A.﹣2或1
B.1或2
C.﹣2或﹣1
D.﹣1或2
答案:C
____ has been reported _____ sales of beef in China will increase.
A.It; which
B.It; that
C.What; that
D.That; that
1物理大气压=()mmHg。