The point is (as a US scientist who has lived and worked in another country, although not Denmark), the issue isn't just whether they can but whether they do. I

The point is (as a US scientist who has lived and worked in another country, although not Denmark), the issue isn't just whether they can but whether they do. In my experience, while English is often the language of science itself in formal settings, people naturally chat among themselves in their native language and if you don't know it, you will be socially isolated, even if they switch to English when talking directly to you.