If you say that there is a paucity of something, you mean that there is not enough of it.
①Even the film's impressive finale can't hide the first hour's paucity of imagination.
②The paucity of fruit was caused by the drought.
③They closed the restaurant because the paucity of customers made it uneconomical to operate.
这个单词最常见的搭配是“a paucity of”。这也是一个外刊中的高频词，《经济学人》一篇关于探索外空的文章也出现了这个表达：
[scode type="green"]on a whim
A whim is a wish to do or have something which seems to have no serious reason or purpose behind it, and often occurs suddenly.
①We decided, more or less on a whim , to sail to Morocco.
②I bought the encyclopedia on a whim .
《经济学人》一篇关于青少年叛逆的文章 How to rebel in China 也出现了这个表达：