—Oh, really? I ____________. I _____________ go and visit him.
A:didn't know; am going to
B:hadn't known; would
C:haven't known; will
D:didn't know; will
抛物线y=ax2的准线方程是y=1,则实数a的值为( )
下列行为不属于社会行为的是()①在山洞中居住的蝙蝠群 ②工蜂喂养蜂王和幼虫 ③草原上的大批食草动物 ④爆发蝗灾时的蝗虫群