Is traffic a big problem where you live? Increased cycling may be the answer. Where are the best pla

39. Riding a bicycle.    
40. The best cities for cycling．
【解析】
这是一篇说明文。文章主要介绍了适合自行车骑行的城市。
【37题详解】
细节理解题。根据第二段的Copenhagen, the city of bikes, is a city where 32 % of workers cycle to work because it's fast and easy.可知，在哥本哈根有32%的工人选择骑自行车上下班，是因为它快捷。故填：Because it's fast and easy.
【38题详解】
词义猜测题。根据第四段的Bristol is the birthplace of ''Sustrans'' — the cycle-route charity which was formed 30 years ago.可知， Sustrans是成立于30年前的一个自行车路线慈善组织。故填：A cycle-route charity.
【39题详解】
细节理解题。根据最后一段的Nowadays, riding a bicycle is also a good way to support low-carbon living.可知，现在骑自行车也是一个支持低碳生活的好方法。故填：Riding a bicycle.
【40题详解】
主旨大意题。根据文章主要内容，尤其第一段的A new report lists the best bike-friendly cities around the world. (一份新报告列出了世界上最好的自行车友好城市。)可知，文章主要介绍了适合自行车骑行的城市。故填：The best cities for cycling．