Translation:It is exactly seven o'clock right now.
For example, when you want to say seventy, you say nana juu, and never shichi juu. I don't know does the same rule apply to hours and minutes... Also when you count up from 1 to 10 it is more frequent that Japanese peole more often prefer shi over yon, shichi over nana and ku over kyuu, but when they count down from 10 to 1 they always say kyuu, nana and yon, and you will never hear ku, shichi and shi. Hope I was a bit helpful...
I would say now=right now=今 which describes it is the current instant in the time space. exactly=sharp=ちょうど which says the time is very accurate (to a minute). They are different concepts which can exist together. i.e. It is seven right now, may be describing 7:05, but is describing the current time. It is exactly seven, is saying the time is 7:00 not 7:01 or 6:59, but I may be talking about the start time of a movie after work today.
Right now differs from now only that right now is talking about the current instant, but now can be broaden to current year/decade e.g. there are more people who have a smart phone now than 10 years ago. You don't say right now.
I don't think so, but you can use it in place of "just" in English, here are some sentences:
「ちょうどいいですよ」"It's just right"
「これはちょうどいい価格です」"this is just the right price"
「味の変化にちょうど良かったです」"it was just good for the change of taste"
I don't think duo gets into it but for most kanji there's two readings, "おんよみ and くんよみ
When the chinese came and taught them to write what they essentially did is they took a japanese word with a similar meaning, slapped the kanji onto it then stripped the chinese word of all tonality and fit it into their syllabary.
殺 (to kill) => サツ、ころ
in most cases, the kun reading is used for single kanji and verbs while the on reading is used for compound kani/"suru" verbs. That being said, counting numbers are "often" onyomi.
shichi is the on reading nana is the kun reading.
Deductive reasoning with some trial and error. You can hover over/tap on words you don't recognize for a definition.
The grammar "X wa Y desu" is from the past intro lessons so that gives you a good start, so you know that it'll be an "X is Y" sentence.
Then insert the new kanji 今 - ima - now
七時 - shichi ji - 7:00
So you have "now = 7:00"
ちょうど is the newest part here, meaning 'exact/precise/sharp'
"Now is 7:00 exactly" or in a bit more comfortable English "It is 7:00 sharp now"
Then if you get it wrong you'll be given the correct answer to learn for next time.
Duo won't accept a typo if that typo creates a new word unfortunately, as small as that word is.
Versions of this sentence without "right" are acceptable, but since there are many ways to do word order and a few different ways to write the words themselves your specific answer may not either be in the database yet (you can hit the report button - "my answer should be accepted" in that case), or you had an error elsewhere in the sentence and the correct 'best' answer given to you was just one that included the word whether or not it was completely necessary.
I didn't encounter Duolingo not accepting the ちょうど either in front or after the time. It may be just that the alternative is missed in this particular question (need the contributors to check), but please double check other parts in your answer as well, because usually it is something wrong in some other parts but the suggested answer shows something very different.
p.s. you misspelled ちょうど as ちゃうど and that may be one of the reasons, for example.
In a previous exercise, I wrote 今は十時半ちょっとです、and it was marked wrong with only difference being ちょっと placed before 十時半.
Now though it is placed after 七時. Is that OK for full hours like 七時and 十時 but not half hours? Or was that a mistake and my previous answer should have been accepted?