英语长难句结构分析难题!
请看以下句子：As more has become known of the many thousands of African plant species and their complex ecology,naming,classification,and mapping have also become more particular,stressing what eas actually present rather than postulating about climatic potential.
开头的as是什么用法啊?若是连词,怎么中间还要加and（and their complex ecology,naming,classification）?主句在哪呀?
请哪位大虾帮忙回答啊?不胜感激!
打错个字，是stressing what was actually present rather than........纠正下是was~~