"Hope we can see each other soon."
I can answer you briefly about this. Similar to English the concept about possibility and ability, and sometimes requests, is not entirely isolated. If we ask "Can you do this?” it can be interpreted as whether the listener is able to do it, or whether the listener will do it. There are also several ways in Chinese to express such related concept. 可以 by its radical meaning is about a possibility - whether it is possible that we see each other; 能 is more about an inherent capacity or ability acquired through training - whether we are able to see each other. In this sentence these 2 words can be used interchangeably.
In some other sentences they cannot. However, it's going to need a lot of pages to iterate all the possible variations. If you have a particular sentence that puzzles you, I can point out which words are acceptable.
It's not very comprehensive, but I hope it helps.
Thank you. Your explanations always help me understand those puzzling differences.
so does 很快 take the place of the day/time in the grammar of this sentence? i.e. goes after the subject before the object in the sentence.
I would break down the syntax like this:
希望 (I) hope (that)
= Main clause
--> 我们 We
= Subject of sub-clause
-->> 可以 + 很快 --> 再见 can + quickly --> see each other again
= adverbial phrases and the verb of sub-clause
The term "adverbial phrases" may not be very well used, but anyway those are phrases that elaborate on the verb. Time can also be used like this.
So it can’t be: 希望我们可以很快见? It has to be 再见？even with no “again” in English?
。。。or would it be ok if I used 见面？i.e. what if we haven’t met yet?
This looks like something I need to understand. Can 见 not stand alone in this sentence?
It is also OK if you use 很快见面. Often Mandarin Chinese calls for 2-character words. Using 1-character word is less often, even though the 2-character word looks redundant.
I wrote: 希望我们能很快再见, and Duolingo didn't accept it. It says the correct answer is, "希望我们很快可以再见". Is the problem that I used 能 instead of 可以, or that I put the 能 before the 很快?
See Keith_APP's explanation near the top of the discussion. It looks like it is acceptable, but not what Duo wanted.
Does 再见 mean 'meet again' as well as 'goodbye'? The literal translation seems to be ' I hope we can part company soon! - exactly the opposite.
Yes 再见 is basically 'meet again'. They use it to say 'goodbye', just like 你好 (you good) is used to say hello.
I don't know where you got 'part' from. The literal translation would be 'hope (希望）we (我们) soon (很快) can (可以) see you again later (再见)'. See Keith_APP's explanation under Muanui's question.