单项选择题
A．Because they may have four seasons in one day. B．Because they often have very good weather. C．Because the weather is warm just like in spring. D．Because the sky is sunny all day.
A．it isn't necessary to know their differences B．there are only a few differences in spoken English C．it will be difficult for others to understand you D．it's hard to remember the differences at the same time
A．About the 6th century. B．Before the 17th century. C．Before the 14th century. D．Before the 15th century.