阅读短文，选择正确答案

     It was a sunny day last Sunday.  Liu Mei went shopping with her mother.  On her way to the shop, they met (遇见) an old woman.  The old woman wanted to see her husband (丈夫).  He had a flu and was ill in hospital.  But she did not know the way to the hospital. Liu Mei asked a policeman.  He told (告诉) her to take the No. 11 bus.  Liu Mei went with the old woman to the hospital and her mother went shopping by herself. Forty minutes later, the old woman saw her husband.  Liu Mei left the hospital and went to the bookstore. She did not wait for their thanks.

②一个挨着一个排成一排

你要研究的问题是：正方体个数与拼成的长方体表面积之间的关系．

探索过程：

根据你的发现填空．

当正方体个数为10时，所拼成的长方体表面积是____平方厘米．

当正方体个数为a时，所拼成的长方体表面积是____平方厘米．

当拼成的长方体表面积是202平方厘米时，正方体个数是____．

如图，已知矩形OABC中，OA=2，AB=4，双曲线y=$\frac{k}{x}$（k＞0）与矩形两边AB、BC分别交于E、F.

（1）若E是AB的中点，求F点的坐标；
（2）若将△BEF沿直线EF对折，B点落在x轴上的D点，作EG⊥OC，垂足为G，请证明△EGD∽△DCF，并求出k的值.

以下事例能体现“舍小家，为大家”精神的有(　　)
①三峡移民②为街道整齐美观某单位拆掉副楼③有些住户在街道内存放杂物、自行车等④为单位集体利益偷税漏税

9的平方根是 ____ ____的立方根是﹣2