Evaluate the sentence with "this," "that," "these" or "those." Identify the subject and object of the sentence.
Look at this example: "This is my bag." Notice that "this" is a subject that refers to the object, "bag." Subject-object references are the easiest ways to recognize the meaning of a demonstrative pronoun.
Look at this next example that does not have a subject-object reference: "The black dog does not like this." Notice that "dog" is the subject and "this" is the object but they are not the same.
Make note that in the example, "The black dog does not like this," the demonstrative pronoun "this" is taking the place of something that the dog does not like.
Read the entire paragraph or sentence or two before the use of the demonstrative pronoun. Look for the name of a place or thing that it may point to.
Look at this example: "This does not make sense." Notice that in the example "this" is the subject because it replaces some physical thing that is incomprehensible.
Repeat Step 5 to see what the subject, "this," refers to.
Keep plurality in mind. Note in this example, "These are so much fun," that "These" refers to more than one thing. Look for a group of things in prior sentences to learn the relationship.
Look at the examples: "This gift is nice" and "These gifts are nice." Notice that "this" and "these" describe the subjects, "gift" and "gifts." "This" and "these" place the gifts close to and in the physical presence of the speaker.
Read the examples: "I like that gift" and "I like those gifts." Notice that "gift" and "gifts" are objects in these sentences and "that" and "those" place a physical distance between the speaker and the gift or gifts.
Identify the object of the preposition in the following sentence: "I want one of those gifts." Make note that the descriptive adjective "those" describes the preposition object "gifts" while placing the gifts at a distance from the speaker.