the tip of an (or the) iceberg the small perceptible part of a much larger situation or problem which remains hidden.
☞ This phrase refers to the fact that only about one fifth of the mass of an iceberg is visible above the surface of the sea.
2002Focus Rumours of BSE equivalents in lamb and chicken are just the tip of the dodgy-eating iceberg.
英语词组固定搭配大全包含15956条英汉双解词组,基本涵盖了全部常用英文词组、短语的翻译及用法,是英语学习的有利工具。