看不懂这句话,This river is one third as long as that river原文意思是：这条

看不懂这句话,
This river is one third as long as that river
原文意思是：这条河只有那条河的三分之一长.
as long as一个是只要的意思还有是和什么一样的意思,我怎么理解也觉得意思不对啊.
好像楼下的没解释清楚。我的意思是按字面意思来翻，这条河三分之一长和那条一样。怎么翻也和原文意思不对啊。