What one learns is not what one applies in work, and what one applies is not what one has learned; a significant disconnect between academic knowledge and practical application, or theory and practice.
他抱怨自己大学里学的专业知识，在现在的工作中几乎学非所用，感到有些失落。
He complained that the specialized knowledge he learned in college was almost completely irrelevant to his current job, feeling a bit disheartened by this mismatch.
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