a sea of people?
There's always a sea of people everywhere during national holidays. 國定假日時,到處都人山人海。
抱歉, a sea of people 中文說人潮。
a big crowd of people?
A big crowd of people tried to board the train. 人山人海的人試圖登上列車。
抱歉, a big crowd of people 是一大群人,try to 是想,不是試圖
用本土說法教英文,不是更棒?
韓國瑜的造勢場人山人海。Han's rally was jam-packed.