the robots have been sent to repair the damaged nuclear power station in Japan
问题描述：
the robots have been sent to repair the damaged nuclear power station in Japan
It was the first time that the robots __have been sent____________ to repair the damaged nuclear power station in Japan.横线处为什么用现在完成时?
横线处改为 had been sent
不好意思打错了
答
had been sent是对的.it was the ,time that 用过去完成时.改为 were sent 可以吗这是固定的。如果前面是一般现在时就用现在完成时。