Is there a difference between "we" and "wij"? Sometimes one is marked wrong, other times both are accepted.
The difference should be audible in an audio exercise. When translating EN > NL, 'we' and 'wij' are pretty much interchangeable unless you (don't) want to stress the word. See also here.
Shouldn't "We are having strawberries" be correct too?
In English, this would mean 'we are eating strawberries', for example in the sentence 'we are having strawberries for dessert'. The Dutch sentence doesn't mean this.