A、Compilation fails.

B、An exception is thrown at runtime.

C、Synchronizing the run（） method would make the class thread-safe.

D、The data in variable "x" are protected from concurrent access problems.

E、Declaring the doThings（） method as static would make the class thread-safe.

F、Wrapping the statements within doThings（） in a synchronized（new Object（））{} block would make the class thread-safe.