When at Harvard, he spent a lot of time imagining how the world ______ over the next 10 or 20 years.
A.changed B.has changed
C.will change D.was going to change
When at Harvard, he spent a lot of time imagining how the world ______ over the next 10 or 20 years.
A.changed B.has changed
C.will change D.was going to change
D