When people learn foreign languages, they tend to reach a certain level and then plateau, i.e. stop learning and developing. I am sure you are familiar with speakers of English (or of your native language) who can't pronounce particular words or sounds, who use the same wrong word every time or who say things the way they would sound in their own native language. A dear Belgian gentleman and friend of our family once said, "I am not visible," to mean, "I am not presentable." Russian teachers of English stubbornly insist on calling school homework 'home tasks' (домашние задания). My Italian aunt, when travelling as a passenger in the car, used to urge the driver to "take over" the vehicle in front. When I moved to Russia I referred to a planning meeting ('planiorka') as a floorplan ('planirovka'). Native speakers of German will say things like, "Are you coming with?" (Kommst du mit?) When castigating bad behaviour,...