补全对话（每题2分，共10分）

根据下面的对话情景，在空白处填上一个适当的句子，使对话的意义连贯、完整。

A: You look worried. ①______________?

B: Miss Gao told us to write a letter to our pen friends, ②______________.

A: Can’t you write a letter?

B: ③______________.  But she told us to write in English. I’m weak in english. ④______________?

A: you can read the passage on Page 15 of our book. It’s a letter from an english girl. Read it again and again until you understand it.

B: But I don’t know how to use some English words.

A: ⑤______________.  You can look them up in an English-Chinese dictionary.

B: You are right. Thank you very much.

一个圆形花台直径是20m，为这个花台围上一圈护栏．护栏的长是多少米？这个花台占地多少平方米？