"I go to sleep at eleven p.m."
Technically there's not even an "I", as I understand it the sentence literally reads "PM-11-hour-at sleep," and the "I" is implied. Right?
In very casual conversation the "I" might be omitted in English, too, like someone commiserating with a co-worker, "Sleep at 11, wake up at 3." But it would be just as likely for them to say it any other way, whereas in Japanese I get the impression that not acting sufficiently casual in casual scenarios can make you seem stiff as much as acting too casual in polite scenarios can make you seem rude. I mean, even that is true in English, too, just moreso in Japanese. Like there are rules for how to be casual.
I'm Brazilian and I also speak Portuguese, of course. Well, in Portuguese we can omit the personal pronouns as well as Japanese, thus I have an idea of how to deal with this "problem". But I think Duolingo could tell us how to speak in casual and polite scenarios, tell us not just the grammar but how to use it and understand it and improve the app as well as its interface. (Sorry for my English)
The hover-over hints for "p.m." are missing. A logical hint here would be to give "午後 / ごご" as a hint for "p.m."
I reported this. I would really like to see this fixed / corrected soon. I feel a bit frustrated because some of these things are so straightforward that I feel like I could fix them myself, if I had the tools / authority / autonomy to do so, even though I don't really know Japanese very well...but like, I report them and then time lags on and on and they're not fixed.
Never feel bad about asking a question, especially since the goal of this app is learning. My understanding is that if you wrote the hiragana for PM after the hiragana for the time (11 in this case), it would be about as incorrect as saying "PM 11" as opposed to "11 PM" in English. Someone please correct me if I'm wrong.
に is the appropriate particle to use here because it is used to indicate that a specific location (in space or time) is the target or endpoint of a verb.
On the other hand, へ is used only for locations (in space, not time) as a guide to indicate the direction of a verb. For example:
に行きます【がっこうにいきます】= "I go to school" ("school" is my intended destination/"school" is the point of my movement)
へ行きます【がっこうへいきます】= "I go towards the school" ("school" is just a marker to show the direction of my movement/whether or not I arrive at "school" is irrelevant)
If we do the same thing for time:
に起きます【しちじにおきます】= "I wake up at 7:00" ("7:00" is the point of my movement/the specific time it takes place)
へ起きます【しちじへおきます】= (doesn't make sense in Japanese) "I wake up towards 7:00" ("7:00" is just a marker to show the direction of my movement, which doesn't make sense because the verb is present tense so there's only one direction time can go in. What actually happens at 7:00 is irrelevant, so is what time I actually get up).
十一 is pronounced じゅういち, but the characters 十 and 一 can have different readings when combined with other characters, for example 一つ = ひとつ and 十日 = とおか.
Is that what you meant? Or:
Individually, 十 is pronounced じゅう and 一 is pronounced いち. Typically when you combine numbers with only other numbers, their on'yomi is used (4 よん and 7 なな are exceptions though).
I agree that Duo's structure isn't really the best for new learners, but unfortunately, memorizing the characters is a huge part of learning Japanese.
(I know you probably meant memorizing the order of the characters without any real understanding, but I just wanted you to know what you're in for ;) )
I don't know if it's the best resource out there, but I found this site (https://www.freejapaneselessons.com/lesson06.cfm) really helpful as a reference when I started learning about verb conjugations. Lessons 6 through 8 deal with verbs.
As for your last question, I'm not sure what you mean by 寝き. Maybe you meant 寝る? In which case, have a look through the table in lesson 8 on that website ;)
Yes and no. 24 hour time is indeed very common, but in my experience, Japanese speakers would generally tend to write 23時 or 23:00, and say 午後十一時.
Sidenote: Kanji is seldom used for writing numbers in Japan; pretentious "fancy" restaurants putting them on their menus are really the only place you're likely to see them.