Which three statements describe the functionality of the DO_KEY built-in?（）
- AIt accepts both a built-in and a key name as argument.
- BIf no key trigger is defined, the specified built-in executes.
- CIts parameter must be specified in upper case, enclosed in single quotation marks.
- DIt performs the same task as if you pressed the function key associated with the specified argument.
- EIt executes the key trigger that corresponds to the built-in specified as its parameter.&e