to make use of a source of energy, knowledge, etc. that already exists 利用，开发，发掘（已有的资源、知识等）
~ sth
We need to tap the expertise of the people we already have.
我们需要利用我们现有人员的专业知识。
~ into sth
The movie seems to tap into a general sentimentality about animals.
这部电影似乎在激发人们对动物的普遍怜惜之情。