Phrasal verbs are a hidden problem for estimating English vocabulary competence (as was alluded to earlier in this thread), because they play serious havoc with the idea of &quot;knowing&quot; a word. If you asked English learners if they knew the meanings of &quot;work&quot;, &quot;in&quot;, &quot;out&quot;, and &quot;off&quot;, most would say yes at a pretty early stage of their English education.<p>But that doesn&#x27;t mean that they&#x27;d necessarily correctly interpret (or produce) &quot;work in&quot; &#x27;incorporate (in a narrative or plan), &quot;work out&quot; &#x27;resolve (a problem); deduce (a solution or consequence); deliberately perform physical exercise&#x27;, &quot;work off&quot; &#x27;eliminate (a debt, obligation, or excessive food intake) through effort&#x27;.<p>And there are hundreds more of those combinations with meanings that need to be learned independently.