Question

His grandfather died three years ago.（同义句转换）

____ _____three years____his grandfather died.

Answer 1

It was three years since/ago his grandfather died.
过去时的话用since和ago都是可以的，ago的后面也可以加that
例句：
It was three years since (= ago) the great man died.
这位伟人过世的时间是三年以前。

下面两句完成时，一定要用since
It was years since I had seen her.
我有好多年没见到她了。
It was three years since he had died.
他去世已经三年了。

用that在话前面要有later或者ago，例句：
It was only three years later that I met my Shifu.
直到三年多之后，才遇到我师父。”
It was three years ago that he moved to the big city.
是三年前他迁到这个城市的。

希望对你有帮助~

Answer 2

同2楼

Answer 3

It was that