ateba fi os gwelwch yn dda - Care should be taken not to mix dy and eich, ti and chi in Welsh.  Dy and eich can both mean 'your', and ti and chi can both mean 'you'.  However, ti and dy are the second person singular forms and signify familiarity when addressing an individual.  Chi and eich are the plural forms but may also be used when addressing an individual in a more formal context.  Eich and dy should not be used together when addressing the same object.