1. Some students posted a lot of unkind comments, making fun of my pose.

2. Some students posted a lot of unkind comments while they made fun of my pose.

3. Some students posted a lot of unkind comments while they were making fun of my pose.

4. Some students posted a lot of unkind comments, which made fun of my pose.

5. Some students posted a lot of unkind comments, and they made fun of my pose.
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Q1: Which one is smiliar to #1, #2 or #3?
Q2: Do #4 and #5 mean #1? In #4, 'which' refers to 'unkind comments,' right? In #5, does 'they' refer to 'a lot of unkind comments'? Or does 'they' refer to 'Some students'?

All the sentences mean about the same thing as #1, yes.

In #4, yes, the antecedent is "comments."

In #5, "they" refers to "students" since both "students" and "they" are the subjects of their own clauses. If "they" were meant to refer to "comments," the word "which" would have been used, as in #4.

Thank you for your help.

4. Some students posted a lot of unkind comments, which made fun of my pose.

5. Some students posted a lot of unkind comments, and they made fun of my pose.

5-2. Some students posted a lot of unkind comments, and they were making fun of my pose.

6. Unkind comments made fun of my pose.

(Can we use Sentence 6? In #4, since 'which' means 'unkind comments,' it seems that we can use #6. Am I right?
Which one is better, to use 'the past tense' or 'to use the past progressive tense'?)

Yes, 4 and 6 have the same meaning, although it seems odd to have the abstract word "comments" be the subject of an action verb "made." It's the people who are making the comments, right?

If the verb's action is in the past and it's over with, then use the simple past.

If the verb's action is in the past and continued for quite a while, then past progressive would be okay.

Q1: Among the options provided, sentence #1 is most similar to sentence #2. Both sentences use a participle phrase ("making fun of my pose") to describe the action of the students posting unkind comments. However, there is a slight difference in the tense used. Sentence #2 uses the past tense "made fun of," while sentence #1 uses the present participle "making fun of." Overall, both sentences convey the same meaning.

Q2: Sentence #4 and sentence #5 can be understood as conveying a similar meaning to sentence #1, although there are slight differences in the phrasing.

In sentence #4, the relative pronoun "which" refers to "unkind comments," indicating that the unkind comments themselves made fun of your pose. So yes, in this case, "which" refers to the "unkind comments."

In sentence #5, the pronoun "they" refers to "Some students." So in this context, "they" refers to the students who made fun of your pose. The phrase "they made fun of my pose" shows that it was the actions of the students (not just their comments) that made fun of your pose.

It's important to note that the differences in phrasing between these sentences may affect the emphasis or clarity of the statements, but the general meaning remains similar in all cases.