对比类说明文通常通过对两种或两种以上的不同事物，或者同一种事物的不同情况进行比较，从而得出结论。写对比性的文章，只要把两个事物描述清楚即可，但是需要注意描写的顺序。一般来说有两种顺序：第一种是分开描述两个事物，把其中一个写完之后，再写另一个；第二种是同时描述两个事物，就某一方面进行对比。
1．比较地理位置或历史(地位)：
①Shanghai is situated on the estuary of Yangtze River of China while Hong Kong is located on the eastern side of the Pearl River Delta.
②...is an old city with a long history，while...is a relatively new city.
③Shanghai is the largest industrial city in China while Hong Kong is a global centre of trade.
2．比较人口、面积、交通等：
①There are more inhabitants in...than in...，so it is more crowded in...
②Hong Kong has a total area of...which is slightly larger than that of Shanghai.
③In terms of area/population，...is twice (three times...)as...as...
④The means of transport in...is...，while in...，it depends mostly on...
⑤Compared with...，...is more...than...in...
3．列举相同点：
①In spite of these differences，both cities share many similarities，for example，...
②Both cities are famous for...
③The two cities are similar to each other in...
4．其他常用句式：
①If we compare the two cities，we can find both differences and similarities.
②The climate of Beijing is better than that of London.
③In addition，they are both capital cities，which makes them famous in the world.
