The proper use of prepositions is quirky and hard to master. In the Lumberjack Part 1 writing exercise, the phrase in English is, "he was filling up his sleigh with branches". I thought "avec" was too literal and did not sound "French". I wrote, "Il remplissait son traîneau des branches" because "de" can mean "with" and there were multiple branches.
The correct answers are: "remplissait avec des branches" or "remplissait de branches".
Can someone please explain why "de" becomes the plural "des" after "avec" but is the singular "de" when used alone? Thanks.
PS - I think a unit devoted just to the quirks of prepositions would be helpful as well as a vocabulary unit with all the everyday idioms that use etre, avoir, pouvoir, faire, mettre, tenir together with y or en in sentences like "je n'y suis pour rien" or "je n'en peux plus." It's the little simple words that sound the most "French" but are also the most difficult to master. Thanks again.