英语翻译于是他向身边的行人询问.而这个行人也不知道,王先生便道了谢去问那边的警察.警察告诉了他.

He asked the pedestrian but they had no idea.Mr. Wang said thanks and asked the police over there.

then he ask other people,but this people also don't know.Mr wang said thanks to him and ask the policeman,and the policeman told him.
用过去式写的 可能不太准确 见谅

Mr.Wang then went to ask the passerby, who turned out to know bothing abou it. After saying thanks, he went to the policeman for help and got the answer he wanted eventually
鉴于中英文中，人称代词的交代顺序，还有措辞和行文习惯，我的翻译如上
请楼主斟酌，合则采纳，不吝追问

then he ask the pedestrians beside him,but the pedestrians donot know either, so Mr.Wang go to the police after he thanks the pedestrians. the police told it to him.

Then he enquired a passer-by,yet the latter did not know neither.Mr.Wang thanked him/her(任选,缺上下文,故不知道是男是女) and went to ask the policeman over there and,this police man told him information he needed.