求翻译：而在国际上发展压缩天然气汽车的推动力已由最初的“已气代油、解决石油短缺问题和改善汽车能源结构”转变为“降低汽车污染物排放、改善大气环境”。是什么意思？

In the international development of compressed natural gas vehicles on the driving force has been the first "gas on behalf of the oil has to solve the oil shortage and improve the car energy structure" to "reduce vehicle emissions, improve the atmospheric environment."

And, at the international development on compressed natural gas vehicles have been the driving force behind the original "has gas generation oil, solution to the oil shortage and improve motor energy structure" to "reduce motor vehicle emissions of pollutants, improve " Atmospheric environment.

But internationally develops the compression natural gas automobile propelling force by initial “to be mad a generation of oil, the solution oil shortage question and the improvement automobile energy structure” transforms for “reduces the automobile pollutant emissions, the improvement atmospheric

And in the international development of compressed natural gas vehicles driving force has been reduced from the initial "gas instead of oil, oil shortage problem resolution and improve automobile energy structure" into "lower vehicle pollutant emissions and improve the atmosphere".

But internationally develops the compression natural gas automobile propelling force by initial “to be mad a generation of oil, the solution oil shortage question and the improvement automobile energy structure” transforms for “reduces the automobile pollutant emissions, the improvement atmospheric