下列图形中，既是轴对称图形又是中心对称图形的是（　　）

A．矩形

B．平行四边形

C．等腰梯形

D．等腰三角形

___________it in the flesh, I would never have known the drought in southwest China is so serious and people are suffering so much.

A．Had I not seen

B．If I did not see

C．Should I not see

D．Were I not seen