"I have a party for twenty-four hours."
It does have subtle difference. Compare "I have a party for 24 hours" and "I have a 24-hour party." For the former, it may mean that the party is more than 24 hours but I just take part of it for 24h only. The latter one means the party lasts for 24h (but I can participate only 6 hours for example).
When you start a sentence with a unit of time, like today, or 24 hours, it doesn't need to be followed by a particle. Much of the comments in this lesson are people trying to add a particle where it isn't needed and is therefore bulky, excess. If it helps, imagine taking a brief pause after stating a unit of time. That's all the seperation you need. Hope this helps.
OK. The reason is that you cannot put を after 24時間. 24時間 is not the direct object of the action "do." It is the time span. You can put は or も after 24時間 to bring up the topic, or まで to indicate the boundary. Other than those, no particle is permitted unless you use some forms like にわたって.
No, it is not grammatically correct. 24時間 (like other counters) acts as an adverb, not a direct object.
A direct object associates with a transitive verb to give the context of what is acted upon by the verb. A prepositional phrase gives the context of any additional information when the action is taken place. The prepositional phrase consists of a preposition and an object of the preposition, and can describe both a transitive verb and an intransitive verb.
For example, in English:
- I brush my teeth. (my teeth is a direct object of the transitive verb brush)
- I go to the market (the market is an object of the preposition to describing the intransitive verb go)
- I put a pen on the table. (a pen is a direct object of the transitive verb put, and the table is an object of the preposition on)
- 歯を 磨きます (歯 is a direct object of the transitive verb 磨きます, followed by the direct object particle を)
- 市場へ 行きます (市場 is the direction of the intransitive verb 行きます, followed by the direction particle へ)
- テーブルに ペンを 置きます (ペン is a direct object of the transitive verb 置きます, while テーブル is the location)
In the majority of cases, you will find the transitivity between English and Japanese are the same. So when English verb requires a direct object, Japanese verb counterpart often requires a direct object too. When English verb has a prepositional phrase, Japanese sentence often contain a particle phrase.
In the current sentence "I party for 24 hours," "Party" is an intransitive verb and "24 hours" is an object of preposition, not a direct object. In Japanese the way to represent 24 hours is to treat it as a counter (no particle is used) so the Japanese counterpart is 24時間パーティーします.