a tip of the iceberg 冰山一角；冰山露出水面的小尖顶；冰山之一角

【例句】
Jumps lists are just a tip of the iceberg, an opening shot in what will probably take them several more iterations to complete.
跳转列表只不过是冰山一角，后续还有更艰难的工作有待完成。

However, it is only a tip of the iceberg.
然而，这只是假新闻的冰山一角。