选出相对应的答语。

①Do you like this shirt? ____       A. It's green.

②What do you have? ____          B. No. It's soft.

③What colour is it? ____             C. Yes, I do.

④Is it hard? ____                         D. I have a dress.

⑤What do you need? ____          E. I need a sweater.

正八边形地板砖，能铺满地面，既不留下一丝空白，又不相互重叠吗？请说明理由．

建筑工地上，起重机几分钟内就能把所需的砖送到楼顶，如果人直接用滑轮组来提升则需要几个小时，其原因是（　　）