甲、乙、丙三个数的平均数是7.5，则甲、乙、丙三个数的和是______．
7.5×3=22.5；
答：甲、乙、丙三个数的和是 22.5．
故答案为：22.5．
—Tony, come down and help me with the heavy box!
— Come on! I _______ all day long．Get Peter to do that!
A．work
B．had been working
C．had worked
D．have been working
现代数码成像技术比古老的神话更善于制造的是（）
A.虚拟现实
B.生活真实
C.悲剧效果
D.喜剧效果
