中国大学MOOC: Both ‘clear’ [l] and ‘dark’ [ɫ] are formed with the tip of the tongue touching the teeth ridge. The only difference is that in the articulation of the ‘clear’ [l], the back part of the tongue is raised towards the hard palate. In the articulation of the ‘dark’ [ɫ], the front part of the tongue is raised towards the soft palate and slightly velarised, with a concave upper surface.