No, in French the only times there are verbs without subject is the imperative (giving a command) infinitive(recevoir=to receive) or present participle (en recevant = in receiving)
We have “une cave”, not “une grotte”. In our region in France and in many others, “une cave” is where wine is made or stored. Our “caves” have been there for some 900 to 1000 years. They were excavated for shelter providing limestone for the building of churches, châteaux, houses. It was later that they discovered how useful these “caves” were for wine. I think “une grotte” would be a natural formation but I don’t know.
I still feel that "cellar" is the better word in English.
If you put a lockable/closable entrance on a cave then it becomes a cellar if it is used for storage or a grotto if it is used as a tourist attraction.
I suppose there is a third possibility - it might become a mine.
I agree. I was using Duolingo for several weeks before I even realised they were there (!).
If I really don't understand a phrase then I run it through Reverso Context and between the two wrong opinions (from Duo and Context) I can usually make an intelligent guess! Sometimes they even agree and no guess is needed.
You might find this interesting to read. http://forum.wordreference.com/showthread.php?t=16124
*explanations. I recommend buying a dictionary. There will never be enough space to convey all meanings in a drop-down list.
"To move" is not the same as "to play". http://www.larousse.com/en/dictionaries/english-french/move/596355
According to French speakers on a language forum, continuer à and continuer de are interchangeable. They backed this up with a number of references.
The link is from @ThanKwee, upthread a bit: