27. If you ________ to something different, for example to a different system, task, or subject of conversation, you change to it from what you were doing or saying before.

A. switch                      B. appeal               C. submit           D. adapt

If you ________ to something different, for example to a different system, task, or subject of conversation, you change to it from what you were doing or saying before．

         A．switch               B．appeal                C．submit          D．adapt