Learn Dutch: Waarmee had hij gegooid als de scheidsrechter niet had gekeken? - What would he have thrown if the referee had not been looking?

This sentence uses the double past perfect structure to express a past counterfactual (a hypothetical situation in the past). Instead of using the longer zou hebben gegooid (would have thrown), Dutch simply uses the past perfect had gegooid in the main clause to match the had gekeken in the als (if) clause.

Why does the sentence start with Waarmee instead of Met wat?

In Dutch, when you combine a preposition like met (with) and the question word wat (what), it transforms into a pronominal adverb. The structure becomes waar + preposition. Because met irregularly changes to mee in this form, we get waarmee (with what / what with).

Could I change the verb order at the end of the sentence to gekeken had?

Yes! Because als introduces a subordinate clause, all verbs are pushed to the end. When you have an auxiliary verb (had) and a past participle (gekeken) together at the end of a clause, you can place them in either order. Both niet had gekeken and niet gekeken had are perfectly correct.

The English translation says "had not been looking". Why isn't there a continuous verb form in the Dutch sentence?