现代较先进的、上旋力非常强的进攻技术是（）
A.正手提拉球
B.正手快带球
C.加力推球
D.弧线球
参考答案：D
瓜子、核桃、花生等物质含有丰富的油脂，多食不易消化．你验证其中含油脂的简单方法是______．
— Who is knocking at the door?
— _______. [ ]
A. They are the children
B. There are the children
C. It is the children
D. That is the children
