The Turing Test

Here is a characterization of the Turing Test: A nonhuman system will be deemed intelligent if it acts so like an ordinary person with respect to verbal behavior that ordinary people cannot tell that it is not an ordinary person. (a) There are many different behavioral manifestations of intelligence. Why might someone single out verbal behavior for a test such as Turing’s? (b) Why was Turing so confident that a universal Turing machine could be programmed to pass the test?