Questions & Answers about De muur was te hoog, dus we konden er niet overheen klimmen.
Why use er ... overheen instead of just erover?
While erover can mean 'over it', it is often used for abstract concepts (like talking about something) or a static position. By adding heen to make eroverheen, you specifically indicate physical movement across and to the other side of an obstacle. Since climbing a wall involves getting to the other side, overheen is the natural choice here.
Why are er and overheen separated by niet?
Complex pronominal adverbs like eroverheen are usually split in Dutch. The er part prefers to sit early in the clause, often right after the subject or conjugated verb. The prepositional part (overheen) gets pushed to the end of the clause, just before the infinitive verb (klimmen). Negations like niet, as well as other adverbs, naturally fall in the space between them.
Why doesn't dus cause inversion (verb before subject) in the second clause?
The word dus (so/therefore) is special because it can act as either a coordinating conjunction or an adverb. When treated as a conjunction (like en or maar), normal word order applies, as seen here with dus we konden. If you treat it as an adverb, you must invert the verb and subject (dus konden we). Both are grammatically correct, but the non-inverted structure is very common in everyday Dutch.