急需问题答案

A clear environment can help the city bid for the Olympics,which( )will promote its economic development答案为什么是in turn？急需
为什么不选in return

as a result 进而
意思是好的环境可以帮助城市在申报奥运会的时候更有竞争力，而申报成功后，又会促进城市的经济发展

in turn- means like which would help with the economic development

"in turn" here means indirectly:

clear environment ==> Olympics ==> economic development

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If you choose "in return", there must be a meaning such as:

clear environment ==> Olympics ==> even clearer environment

which is not stated in the sentence.

一个良好的环境可以帮助这个城市参加奥运会的申报,同样地,申报奥运会可以为这城市带来经济繁荣.

in turn ---as an equal or related effect.同等作用的.两者是起到同样作用的.

http://idioms.thefreedictionary.com/in+turn

A clear environment can help the city bid for the Olympics,which( )will promote its economic development
好的环境可以帮助城市在申报奥运会的时候更有竞争力，而申报成功后，又会促进城市的经济发展

yuhuashiabcdef的解释基本是正确的.
longman词典对于in turn的解释如下: