*Change* is an ergative verb: 1. As an intransitive verb, its subject undergoes the change: > The English language has changed over time. 2. As a transitive verb, its object undergoes the change: > **Someone** has changed the English language over time. Now we have ***someone*** causing the change. 3. And when you passivize the transitive version, you end up with your ***been*** sentence: > The English language have been changed over time <strike>by **someone**</strike>. We still have *someone* causing the change, but the ***by someone*** phrase has been omitted. So although both sentences work, the ***been*** sentence implies that it's been changed ***by someone***. And that's not really how language change works, so the sentence isn't really true—though it *is* perfectly grammatical. ---- You also ask about three sentences: > 1. How the English language has been changed over time? > 2. How has the English language been changed over time? > 3. How has the English language changed over time? We've already covered the difference between sentences 2 and 3, so I'll just talk about sentence 1. This sentence has the form of an interrogative clause, but main clause interrogatives are usually marked by **Subject-Auxiliary Inversion**. This isn't, so it doesn't work as a complete sentence (except as perhaps an echo question or the like): > how [the English language]<sub>*subj*</sub> has<sub>*aux*</sub> been changed over time It does work as a subordinate interrogative clause: > I wonder [how [the English language]<sub>*subj*</sub> has<sub>*aux*</sub> been changed over time]. It works as a complete sentence if we invert the subject and auxiliary. If we do that, we end up with sentence 2, which is perfectly grammatical: > How has<sub>*aux*</sub> [the English language]<sub>*subj*</sub> been changed over time? Though note, as previously discussed, that this question implies it's been changed ***by someone***, which doesn't entirely make sense.