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 */ }