假如你叫李明,你的澳洲笔友杰克要来北京,请你给他写封信告诉他北京一年四季的天气状况和来京的最佳时机,并给他提些旅游的相关

dear jack
beijing is cold in winter and hot in summer,spring has sand storm and fall very dry.
the best travel tim is in October.
YOU can visite sunmer palace.take enough money and you would have a good journey.
your sincerely
liming