彼岸之澄
前者，还可以用，老外可以听懂。但是 people mountain，就是“中式英语”了。人山人海：最常见的说法就是 a sea of people 。车水马龙：a flow of traffic。
流浪猫想家
不对吧，你这个都是中式英语呀，如果形容街道很多人应该是 there are many people on the street. And traffic is very heavy.
浅陌时光
确切的说有2种 1. huge crowds of people 2. a sea of heads 例如，这条街人山人海，万人空巷。 There are huge crowds of people in this street. or There is a sea of heads in this street.
