在我国经济生活中，有一种“龟兔双赢理论”。龟兔赛了多次，互有输赢，后来龟兔合作，兔子把乌龟驮在背上在河边跑，然后乌龟又把兔子驮在背上游过河，这就是“双赢”。“龟兔双赢理论”给我们的启示是（      ）

已知扇形的圆心角为40°，这个扇形的弧长是$\frac{4}{3}$π，那么此扇形的面积是____ ．

将下列陈述句改成疑问句

①小姑娘天真的心灵，正像一个含苞欲放的花蕾。 ②这些树叶就是从这棵树上飘落下来的。

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加、删除或修改。

增加:在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。

删除:把多余的词用斜线(\)划掉。

修改:在错的词下划一横线，并在该词下面写出修改后的词。

注意: 1.每处错误及其修改均仅限一词;     2.只允许修改10处，多者(从第11处起)不计分。

Dear Tom，

    I'm glad to hear that you are very interesting in Guoxue．Let me to give you a simple introduction to it．

    Generally speaking，Guoxue refers to the excellent traditional Chinese culture，that includes philosophy，literature，history，music，painting and so on．Guoxue has been playing an increasing important part in China，especially for them students．Not only did it tell us how to study，but it also teaches us how to live．More and more Guoxue courses is given in schools of different levels all over China．

    If you want to get better understanding of Guoxue，you are welcome to China to learn it，feel it and enjoy it．I'm sure you'11 benefit from living in two different culture．I'm looking forward to see you soon in China．

Yours，

Wang Kai