If someone asks "How far is Brazil from Argentina", a possible answer is "It's about X kilometers". However, if someone asks "How high is this mountain?" you can answer "It's about X meters high". I think that "It's about X kilometers far" would sound weird, but I don't whether it's correct or not. Could you help me?
Learn English – Different answers for questions with how + adjective
expressions
Best Answer
In sentences like
high and far function as adjectives, and the question asks about a quality of the adjective.
High can be used on its own, intensified, or qualified:
Far can only be intensified. It can't be qualified, and it's odd on its own:
The difference between far and high may be due to direction of measurement. Although we live in a three-dimensional world with mountains, we move on its surface and default to measuring in its two dimensions. High [and deep] can be qualified because when we measure vertically we need to specify that direction; far can't be qualified because it doesn't refer, and doesn't need to refer, to a direction.
If you need to qualify far, you need to use a word which can be qualified like away ("Brazil is 12000 miles away") but that's a different question. Away can't be used on its own in this sense (*Brazil is away) or intensified (*Brazil is very away).