问题
                    
When he looked up, he suddenly found himself_____ by a group of teenagers,_____ looked at him anxiously[ ]
                            A: to be surrounded; which
B: surrounded; who
C: be surrounded; who
D: having been surrounded; which
                        
                        B: surrounded; who
C: be surrounded; who
D: having been surrounded; which
正确答案是:
                        