Translation:Mom is drinking juice and dad is drinking tea with milk.
The explanation is that Duo limits the number of answers we can accept for a single sentence, and with each new translation you add for a given word the number grows exponentially. "Papa" seems like a fairly serious omission though so I added it at the expense of some other theoretically possible but less likely sentences. Daddy, father, dad, and papa are all now accepted, but some other forms that have been suggested such as pop and poppa will not be.
They are added in the form of multiple strings generating answer options. The format is like "[This/That] [man/person] is my [father/dad/papa/pop/daddy/pappy]"
Still, it means someone should enter them and keep track of all the options in every sentence. If someone decides "I think so" is pretty much the same as "I believe so", "I suppose so", "I guess so" and maybe "I fancy so" or "I reckon so"—ideally, you want to check every single sentence with "think" to see if any of these work there too.
It is the major source of inconsistencies you see in the course.
Well, с requires it (when you mean "with"), as do за, под, перед, над.
The Instrumental is also used on its own. Here are a few uses:
- Она рисует карандашом. = She is drawing with a pencil.
- Флаг унесло ветром. = The flag was carried away by wind.
- Здание спроектировано нашим лучшим специалистом. = The building was designed (structurally and architecturally) by our best expert.
- Вечером Василий пришёл домой совершенно пьяным. = In the evening, Vasiliy returned home completely drunk.
- Походка капитана показалась мне странно знакомой. = The captain's gait seems strangely familiar to me.
Yes they do, but they are used differently. "а" is used to join parts of the sentence together and "и" is used to say that things are together. So imagine you want to say "I'm eating fish and chips and you are not!" The first "and" in "fish and chips" would be "и", and the 2nd one which joins the sentence would be "а". Not sure if I explained it well, but read this: http://www.rus-on-line.ru/Exercises/Grammar/13-grammar.html
Now, reviewing the favourite drinks of all the relatives would be a hit!