为数众多(或不多);数目巨大(或微小);众多(或稀少)
thick / thin on the ground
为数众多(或不多);数目巨大(或微小);众多(或稀少)
if people or things are thick / thin on the ground, there are a lot / not many of them in a place
Customers are thin on the ground at this time of year.一年里这个时节顾客很少。
释义来自《牛津高阶英汉双解词典》第 9 版