改错题

The local health organization is believed to be set up thirty years ago when George became the first president
                           A                                                        B                                        C                                                      D

【正确答案】

B 改为 have been set up .

【答案解析】

考查非谓语和时态。题中后面有时间状语 thirty years ago。所以believed to have been done, 所以要把 be set up 改为 have been set up。