一句英语的语法意思的分析

题目

一句英语的语法意思的分析
As the vapor rises higher and higher,the temperature of the surroudings air
becomes lower and lower.Eventually,the vapor loses enough heat to the
surrounding air *to*
allow it to turn back into a liquid.
我用*号标注的to表目的显然是不符合常理的,分析下

答案