For the human study, people spent one hour writing down as many faces from their personal lives as possible. Some examples may include people they went to school with, people they work with and family members. Then, they wrote down famous faces they know, such as actors, politicians and other public people.
At first, they found it easy to come up with many faces. But by the end of the hour, they found it harder to think of new ones. Their change in speed let the researchers estimate when they would have run out of faces completely.
请问作者为何要用"would have run out of faces completely " 不用
"would run out of faces completely"?? 差别在哪呢?
谢谢