<p>"i dont think we want to spend too much time on that"
vs
"i dont think we want to spend too much time on this"
"in the wild, pygmy chimpanzees are found only in an inaccessible region south of the zaire river, and very few are in captivity because of that"
vs
"in the wild, pygmy chimpanzees are found only in an inaccessible region south of the zaire river, and very few are in captivity because of this"</p>
<p>are that and this interchangeable in all such contexts?</p>
<p>Stolen from the internets 
</p>
<p>Use “it” when there is an antecedent that could be feasibly inserted in its stead.</p>
<p>For instance, you could say “give the dog its bone” because you could insert “the dog” for “it”:</p>
<p>Give the dog (the dog’s) bone.</p>
<p>You could also say “give the dog this bone”, but you would have to be holding it. “This” implies spatial, temporal, or referential nearness.</p>
<p>You could even say “give the dog that bone”, but this implies that you most certainly aren’t holding it. “That” implies spatial, temporal, or referential distance.</p>
<p>To take your examples one-by-one:</p>
<p>–
A : I swim every day
B: It’s good / that’s good. <—You would say “that’s good”. It wasn’t you who swims. There is distance. There is no antecedent for the pronoun, “it”.</p>
<hr>
<p>A: I can help you with your homework
B: I really appreciate it / that,/ this </p>
<p>I’m sad you thought of this one. This one is a special case. Notice that there is no antecedent for “it”, and there is distance (it is not you who will be helping). The proper way to say this is “I really appreciate that.”</p>
<p>BUT</p>
<h2>This is a spoken-English colloquialism. A native-English speaker would say “I really appreciate it.” The implied antecedent here is “your help.” It is technically incorrect, but this is how everyone talks. Confusing, I know. Sorry.</h2>
<p>The governement is laid back and doing nothing about it. That / it/ this makes things worse.</p>
<p>Here you would use “this.” This is because it is an idea which you have just said. You are close to it, referentially speaking.</p>
<hr>
<p>I hope this helps a little.</p>
<p>[It</a> vs. that vs, this](<a href=“Post Not Found”>It Vs. That Vs, This?)</p>
<p>[YouTube</a> - 2010 Kia Soul Hamster Commercial | Black Sheep Kia Hamsters Video](<a href=“- YouTube”>- YouTube)</p>
<p>^ You sir are a genius!</p>
<p>The difference between “this” and “that” is generally a question of distance. “This” is usually “here” while “that” is “over there” (just an example. In the sentences you list, it’s more ambiguous.</p>