"That man reads that."
Translation:그 남자가 저것을 읽습니다.
it's not explained and it doesn't matter in duolingo. both will/should be accepted. it willl only make a difference when you put it to practical use. use 그 when the one you're pointing to is near the listener and 저 when it's far from you both. as for now, you can just imagine a scenario for yourself and try to use the proper words according to the image in your mind
Sometimes "that" is a demonstrative and other times "that" is a noun. We need to append 것 to turn the demonstrative into a noun.
Specifically, "That man reads that." can be rewritten as:
"That man reads that (thing)."
Therefore when we translate the sentence into Korean, we need a noun for "that thing". Furthermore since 저것 is the object of the verb 읽다 ("to read"), we need to attach the object marker 을 as well. Hence we arrive at the given translation:
그 남자가 저것을 읽습니다.
Be warned, 것 will often be contracted in spoken Korean. Here are some examples:
- 저것 = 저거 ("that thing over there")
- 그것이 = 그게 ("that thing" as the subject of the sentence)
- 이것을 = 이걸 ("this thing" as an object of a verb)
- 저것은 = 저건 = 저거는 ("that thing over there" as the topic of the sentence)
Bad grammar. I'm assuming you wrote "저것을 남자가 그 읽습니다".
- 그 is a demonstrative. It translates to "that" and it needs to be placed before a noun.
- 저것을 is a noun tagged with the object marker. It translates to "that thing over there" and it should be placed between the subject of your sentence and before the verb. In this sentence 남자가 is tagged as your subject.
The English sentence "That man reads that." has two instances of the word "that", but they are used differently and are grammatically different. The first instance of "that" is a demonstrative modifying the subject of the sentence "man". The second instance of "that" is a noun referring to "that thing".