Она думала о последнем листе — дума

Она думала о последнем листе — думала о нем, быть может, уже не один час.

Results (English) 1:

She was thinking about the last worksheet is thinking about it, maybe more than one hour.

Results (English) 2:

She thought about the last page - think about it, maybe for more than one hour.

Results (English) 3:

She thought I was on the last sheet - thought about it, it may be, is already not one hour.