以下多边形中，既是轴对称图形又是中心对称图形的是【  】

A．正五边形

B．矩形

C．等边三角形

D．平行四边形

根据句意及首字母提示补全单词。

1. China's flag has five yellow s_________ on it.

2. Beijing is in the n_________ of China.

3. Wang Fei is a very f_________ singer in China.

4. I want to v_________ Buckingham Palace some day.

5. I can't fly a kite (放风筝). It's not e_________, I think.