The reason________he didn't come was _____he was seriously i

他 没 来 的 原 因 是 他 车 祸 重 伤 .
他 之 所 以 没 来 是 他 在 车 祸 中 受 了 重 伤 .
The reason why he didn't come was:他 没 来 的 原 因 是
he was seriously injured in a car accident:他 在 车 祸 中 受 了 重 伤
The reason (why he didn't come) was that--- That was the reason.那 就 是 原 因 .原 因 就 是 那 个 .
That was the reason why he didn't come:he was seriously injured in a car accident.

The reason__why______he didn't come was __that___he was seriously injured in a car accident.

The reason___why_____he didn't come was ___that__he was seriously injured in a car accident.
the reason why 固定搭配“...的原因”
后一空that，宾语从句的引导词