题目

This is the first time astronomers ____the whole process of a black hole ___a star, from its first
to nearly final bites.
A see eat B have seen eating C saw eaten D had seen eat
这个句式是不是用完成时呢?

提问时间：2020-12-27

答案

是用现在完成时
It/This is the first/second/……/last time that +现在完成时
It/This was the first/second/……/last time that +过去完成时