是介词,意思是：沿着.
down the narrow street,沿着狭窄的街道原句是这样的He got up and ran across the square and then down the narrow street. 介词的话不是很奇怪。。。还有，能帮忙翻译下吗谢谢He got up and ran across the square and then down the narrow street. 他起床（或者：起来）后跑过操场，然后沿着狭小的街道（继续跑下去）。这句话中down是介词。例如：he walks down the narrow street to school everyday