1. To make a snowman was fun.

(What is the part of speech of 'fun'? A noun of an adjective?)

2. I make it a rule to get up at five in the morning.

3.I regard it natural to study math every day.

(Are the two sentences grammatical?)

4. The boat rocked so much that I got sick.

5. The boat rocked so much that I got seasick.

(Does 'sick' mean 'seasick' in the sentence? Are both the same? Thank you for your help. Have a great weekdays.)

1. fun = adjective

2 and 3 are fine.

4 and 5 are fine, too -- and yes, on a boat "sick" and "seasick" usually mean the same thing.

1. To determine the part of speech of a word, you can examine its role and function in a sentence. In the sentence "To make a snowman was fun," the word "fun" is functioning as a noun. It is the subject complement, describing the experience of making a snowman.

2. The sentence "I make it a rule to get up at five in the morning" is grammatically correct. Here, "it" acts as a placeholder or anticipatory subject, while "a rule" is the direct object. The infinitive phrase "to get up at five in the morning" serves as the complement of the verb "make."

3. The sentence "I regard it natural to study math every day" is not grammatically correct. Instead, it should be revised as "I regard it as natural to study math every day." Here, "it" plays the same role as in the previous sentence, and "as natural" functions as an adjective phrase modifying "it."

4. In the sentence "The boat rocked so much that I got sick," the word "sick" refers to feeling unwell due to the rocking motion of the boat. It generally implies a feeling of nausea or physical discomfort.

5. The sentence "The boat rocked so much that I got seasick" specifically indicates that the speaker felt ill due to the boat's motion on the sea. "Seasick" is a more specific term for feeling unwell on a boat in the context of being on the water. So, while "sick" can have a broader meaning, "seasick" is a more precise term to describe the feeling of sickness on a boat at sea.

Thank you for your kind words! I hope you have a great week as well. If you have any more questions, feel free to ask!