I don't understand when to you snel and snelle?
When an adjective comes after the noun (a predicative adjective) it doesn't get the additional -e. It's explained here.
re pronunciation -- is the start of 'zijn' meant to be joined here to the end of the preceding word, or is otherwise different to how it may sound elsewhere?
Why is the plural made with an -s in vogels? It's usually done adding -en, right?
As far as I understand it: if a word ends with an "l" the plural of that word ends in "ls" while in all other cases an "en" is added
When do we drop an e at the end of a word
May I say, "The birds are swift"?