I've seen a lot of 500+ word answers on here, and not I don't think that's a bad thing at all, but for most of the answers, the point isn't conveyed until halfway through the answer.
Simply put, began and spending are a Verb+Infinite pair, in which 2 verbs are used one after another to convey additional information.
Why?
In this pair, began is the infinitive verb and spending is the base verb.
We know this because if we remove began and change the tense of spending to spent, the sentence still conveys the same point but with less detail
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