The weather in Beijing is better than in Guangdong. （错误） 应改为：

（1）The weather in Beijing is better than that in Guangdong.

（2）The weather is better in Beijing than in Guangdong.

 “比较”是发生在两个同类事物之间。具体到句子中，就是两个并列成分间的比较。原句的错误在于：主语是the weather, in Bejing作定语，那么，than后面的成分应该也是the weather in Guangdong 才对，改为句1，用that 代替weather 以避免重复；或者仍用the weather作主语，但比较的成分是两个地点状语：in Beijing 和 in Guangdong，如句2。

一、并列成分（主语之间）的比较，than 后用that 代替主语的例句：

Our price is much lower than that in the international market.  我们的价格比国际市场价格低得多。

The population of Tokyo is larger than that of London.  东京的人口比伦敦的多。

This bread is more delicious than that in the box.  这面包比盒子里的面包好吃些。

Your price is 20% higher than that of last year.  你方价格比去年高出20%。

The engine of your car is better than that of mine.  你的汽车发动机比我的好。

二、并列成分（地点状语之间）比较的例句：

It rains less in London than in Manchester.  伦敦的降雨量比曼彻斯特少。

It's warmer outside than in this room.  外面比这间屋子里暖和。

There are more cars on the road in the summer than in the winter.  夏天路上的车子比冬天多。

How much does sound travel faster in water than in air?  声音在水中比在空气中传播快多少？

It is cooler here than in the bedroom.  这儿比卧室里凉快。