I am currently revising for module exam on groups and symmetry. I can easily identify rotations, reflections, translations and glide reflections that preserve the wallpaper group. However I am struggling to see which of these isometries generate the wallpaper group. For example wallpapergroup
I can see the translations , reflections, and glide reflections but the next question in the exam asks me to list a prove which isometries generate the wall paper group. How can I see/ know what generate the wallpaper group?