_______ many times , he still couldn’t understand it．

A．Told

B．Having been told

C．He was told

D．Though he had been told

灭火救援业务训练手段有（）。

A、利用现有器材装备训练

B、利用建（构）筑物训练

C、利用模拟设施器材训练

D、利用预案训练

E、利用电教设备教学训练