Heidegger and the question

Taken from "Lectures to Heidegger's Sein und Zeit by Benjamin Waters:
http://www.benjaminwaters.org/wat002.0.9.htm#13

“Every inquiry is a seeking. Every seeking gets guided beforehand by what is sought.”(Hei·BT,5) In fact, every genuine question has, according to Heidegger, already a prior understanding of three things: 1. that which is asked about, 2. that which is interrogated in the questioning, and 3. that which is to be found out by the asking (in German 1. das Gefragte, 2. das Befragte, 3. das Erfragte). Essentially the idea is that we don’t ask questions just out of the blue about things that we have no idea whatsoever about. Our enquiry begins with the things that we already have some knowledge of and which we are already dealing with on some level. If I ask even a simple question like ‘how high is this door?’, I already know quite clearly what this thing is that I am asking about—I know what a measurement of height is, and I know what a door is. I already know what it is that I am going to be doing in order to answer my question—that I will be interrogating the door itself with my tape measure. I already know what kind of thing my answer is going to be—a measurement in meters. So questioning or enquiry already starts out from a ground of knowledge, such that the answer comes as something more like the missing piece in a jigsaw than the surprise gift that confronts you when you unwrap a present. Often answering a question is in fact more like merely making connections between bits of knowledge that you already have. (emphasis added)