A、 private synchronized Object o；

B、 void go（） { synchronized（） { /* code here */ } }

C、 public synchronized void go（） { /* code here */ }

D、 private synchronized（this） void go（） { /* code here */ }

E、 void go（） { synchronized（Object.class） { /* code here */ } }

F、 void go（） { Object o = new Object（）； synchronized（o） { /* code here */ } }