I have just had my lunch. I _____ it at home.
A:have had
B:had had
C:had
D:have
做好环境消毒是预防甲型H1N1流感的有效措施,过氧乙酸(CH3COOOH)是常用的消毒剂之一。下列有关过氧乙酸的说法不正确的是( )
2+____=9 ____+6= 6
____-3 =5 ____+____=7