For #4, the question is different than the others because 休み is a noun, not a verb. (Lit. Saturday, Is (your) company on vacation?) When asked this way, the answer should correspond with a noun in the answer. "Yes, (the company is) on vacation" -「はい。休みです」　 Or for the negative,　"No, (It's) not on vacation" 「いいえ。休みではありません」　Or　「いいえ。休みじゃないです。」 ("On vacation" sounds slightly awkward in English, but it just means that the company is closed/doesn't require employees to come in on that day) 休む as a verb means "to take a break/to take a day off" Think means that if the question was phrased 「明日休みますか？」 (will you take tomorrow off?) you would respond with the regular Godan indicative forms はい。休みます。 いいえ。休みません。 An easy way of spotting a noun(adjective) is by looking for "です” In #4, the question uses ですか？meaning that the thing that comes before it is a noun/adjective If a question ends in ますか？ then it is preceded by the verb's root (either Ichidan or Godan)

明日休み”ます” I will take the day off tomorrow. V「休みます」(Verb ますform) ＊negative form ex)明日は休み ません。 明日は休み”です” Tomorrow is a holiday N「休み」＋です(like “is”) ＊Because of です,we find “休み” as a Noun ex)これはペン”です”。This “is” a pen. ＊2 Sometimes,you can make Noun from Verb.(Please ,omit ます from Verb) V「遊びますplay」→ Noun「遊びa play」 ＊3 negative form ex)明日は休み じゃありません。 orではありません。

Unlike 1) and 3) in which those words are verbs, 4) 休み this is not used as a verb here. If the question is for example "明日休みますか" then the negative answer will be "休みません", but here "休みです" it's not a verb and this "休み" is a noun. So the negative form should be 休みではない → 休みではありません。 Verb: 休む　休まない　休みません Noun: 休み　休みではない　休みではありません I hope this makes sense.