读图（阴影表示黑夜），回答下列各题。

根据句意和空缺处所给首字母写单词。
____ I have m________hobbies, such as swimming, rowing and hiking.
____ He said he would never f_________ the trip to Mount Fanjin.
____ We should do more exercise to keep h ________.
____ Tongren have developed r          into a modern city in the recent years.
____ My little sister is so young that she can't look after h________.

关于日本的叙述，正确的是

计算$\sqrt{\frac{b}{5}}÷\sqrt{\frac{b}{20a^2}}$．