Question

7.       that more than 110 people died in the airplane crash (estimate)

据估计超过11O个人死于这次空难。

Answer 1

7. It has been estimated空白处应为一个由it作形式主语的句子，it代替后文中由that引起的真正的主语从句。宜用现在完成时，表动作对现在的影响。