Learn Spanish (Latin America): Nunca olvidaría lo velozmente que abriste el paracaídas. - I would never forget how swiftly you opened the parachute.

To express the intensity of how an action was done, Spanish uses the formula lo + adverb + que + conjugated verb. While lo velozmente que literally translates to 'the swiftly that', in natural English it means 'how swiftly'. It emphasizes the extreme speed of the action.

Why is it el paracaídas if the word ends in '-s'? Is it plural?

Paracaídas is a compound noun made from the verb parar (to stop) and the plural noun caídas (falls). Like many compound nouns in Spanish (such as el abrelatas for can opener or el paraguas for umbrella), it is always masculine and uses the exact same form for both singular and plural. The singular article el tells us it means 'the parachute' rather than 'the parachutes'.

Olvidaría could mean 'I would forget' or 'he/she would forget'. How do we know it means 'I' here?

The conditional tense form olvidaría is identical for the first person (yo) and the third person (él, ella, usted). Without a pronoun or surrounding context, it can refer to any of those. In this standalone sentence, 'I' is just the most natural assumption. If you wanted to remove all ambiguity, you would add yo before nunca.

Could I use qué tan velozmente instead of in this sentence?