Animals in the wild
Elephants are big animals. any actions that change the display must change the equivalent @@Is this computable in a practical time (cf. NP complete) .  Computer science help needed here.  Of course, as in other parts of document, the fact that the equivalent changes is no guarantee that equivalent is correct than it is guaranteed that "alt" text for an image is correct. Python snakes can eat a small goat. technologies have been reviewed for accessibility issues throughout the design phase and have accessibility built-in. Many non-W3C formats require specific applications (often called plug-ins) that are inaccessible or do not work well with assistive technologies. Using W3C technologies will tend to make pages more accessible to more people using a wider variety of hardware and software
Sea turtles can live for a long time. They like to eat fish. Most search facilities require the user to enter keywords for search terms. Users with spelling disabilities and users unfamiliar with the language of your site will have a difficult time finding what they need if the search requires perfect spelling. Search engines might include a spell checker, offer "best guess" alternatives, query-by-example searches, similarity searches, etc