Translation:I will go to a party. I need to dress up a bit.
"I'm going to go to a party, I want to dress up a little." was rejected.
要 is more of a "need" than a "want." In this case, "I need to" dress up is correct and "I want to" is not.
However, other forms of the first English sentence should be accepted, such as "I will be going to a party." Also, the "a bit" part is somewhat redundant. 一下 is there to make the phrase sound less harsh / more conversational. It doesn't literally mean "a bit." If someone was to dress up a lot, in conversation they would still say "打扮一下"
I do feel that "want" can be used here too. You can go to a party and not want to dress up (我不要打扮). Using 需要 (xu yao) can be used to distinguish between need vs. want - but idk if Duolingo has taught this yet, since I'm basing all this on my personal experience (Chinese is my 2nd language for 20 years+).
"I'm going to a party so I want to dress up a bit" was rejected but I think it's fine
I think you need "所以" to express the "so" in your answer (i.e., causation) and that isn't present in this exercise.
True, but at other times Duo has used "so" to join the two independent clauses when one follows from the other even when there is no 所以 because you need to add some sort of non-existent conjunction to replace the Chinese comma splice. Either that or you need to create a second sentence. Having said all that I would consider it too risky to use "so" as the conjunction for the reason you stated. It is usually low risk to use something like "and", although I don't know if that is accepted in this exercise.
"I will go to a party and I need to dress up a bit" should be accepted. That translation for this construction occurs frequently elsewhere in the curriculum
Also "I will go to a party" is a really stilted phrasing that isn't really used
I learned 打扮 as put on make up, I dont think I ever heard a man say 打扮, dress up might be a bad translation
And yet again, 要 has more than one meaning and therefore is subject to interpretation, and therefore having only a very narrow answer being accepted generates loads of comments like this page here. "Need" doesn't necessarily mean that it is out of true necessity, as in the phrase "I need to eat if I want to stay alive." Once you acquire a certain flow in the "vernacular" use of a language, ("everyday" way of using the language versus "learned in a book"), those prickly distinctions tend to meld together and become pretty interchangeable.
My suggestion is this: rather than play gate-keeper with a martinet that strikes everyone who doesn't have the exact string of words, why not enrich the database with either additional solutions or create sentences that leave no room for interpretation.
This particular string: "My car is red; my car is a shade of red; my car is a little bit red; my car is reddish; my car's color is red; red is the color of my car. My car's hue is red.;" contains the same idea: "my car is red." But only one sentence, "my car is red" is simple enough to allow only one translation, with only one acceptable solution: "我的车是红色的." (and yes, someone might justifiably argue "是“ doesn't have to be there).
I honestly think that, for now, the code engine of Duolingo Chinese cannot accommodate a more sophisticated turn of either the English or Chinese languages and might be better off sticking to "Chinese/English basic needs.
Why not? Don't think it's a case of "must" though...just one possible way to express it in English
The Chinese is using what we call a comma splice to join two independent clauses. In English you cannot really do that, so you need to use either a conjunction, a semi-colon or a second sentence depending on the relationship, if any, between the two clauses.
What does 打扮 mean exactly? Dress up as in dress fancily? Put on clothes? Dress up in a costume?
"I'm going to a party and want to dress up a bit." was rejected because I didn't put the extra implied "I" before want. Was trying to make the translation as casual as possible, but it didn't like that.
联欢 or 聚会 is used for saying party, never ever say 派对, they will think you are mispronuncing 排队。。
派对 shall not cause misunderstanding here, because nobody says “去一个排队 go to a queue-ing”.
会(hui4) means "will" in that the action will definitely happen in the future, while 要(yao4) means either "want" or "need".
"I will go to a party. I want to dress up awhile." should be accepted.
According to https://en.wiktionary.org/wiki/%E4%B8%80%E4%B8%8B, "a (short) while; a moment" is also a definition of "一下" and, in my opinion, sounds more natural for conveying a short amount of time than "a bit" as far as "dressing up" goes.
(Usually, I use the second variant of this definition, "a moment", as a translation for "一下", but "dressing up" for "a moment" sounds strange, so I tried "awhile" instead with "a bit" appearing in the suggested answer upon rejection.)
I think you are confusing 一下with 一会（儿）。The first means "a little" as in either the sense of time or amount e.g. 请放松一下 (please relax a little). The second only refers to time. E.g. 请等一会儿 (please wait a moment )。