Learn Dutch: Hoe hard je ook op de toets drukt, de klank blijft zacht. - However hard you press the key, the sound remains soft.

You use the combination of hoe + adjective or adverb + ... + ook. In this sentence, hoe hard paired with ook creates the meaning of 'however hard' or 'no matter how hard'. Without ook, it would just be a standard question asking 'how hard'.

Why is the verb drukt at the very end of the first clause?

The hoe ... ook structure creates a subordinate clause. In Dutch subordinate clauses, the conjugated verb (here, drukt) always gets pushed to the end of the clause.

Why is there no inversion in the main clause (de klank blijft)?

This is a major exception to standard Dutch word order! Normally, when a sentence starts with a subordinate clause, the main clause inverts so the verb comes first. However, concessive clauses like hoe ... ook do not trigger inversion. The main clause keeps the standard subject-verb order: de klank blijft.

I learned that toets means 'test'. Why is it used here?

The word toets has multiple meanings. While it frequently means 'test' or 'exam' in a school context, it also means a 'key' on a piano, synthesizer, or computer keyboard. The context of drukt (pressing) and klank (sound) makes it clear we are talking about a musical key.