Question

4. We all thought it a pity that the conference         . (cancel)

会议竟然被取消了，我们都认为这很遗憾。

Answer 1

4. should have been cancelled should此处不表"应该"，而是意为"竟然"，含"惊讶"之意，其后跟have done结构，表动作已完成。