We will want to teach our students how to perform language functions (but see 3.6.1), and we may well decide which ones are more important for which levels. A problem arises, though, with the actual language used for these functions. We have already seen the request function performed in two ways (‘It’s very hot in here’, and ‘Could you open the window?’), but we could also say ‘Please open the window.’; ‘How about opening the