Now, complete these rules! 1. We use + past participle to say that an event or situation was possible in the past.

2. We use + past participle to say we are sure something didn't happen or was impossible in the past.

3. We use + past participle to say we are sure that something happened or was true in the past.

The great depression, which lasted throughout the 1930s in the united states, affected many people, and it had a devastating impact on an entire subset of the u.s. population. modernist writer john steinbeck wrote about the toll the depression took on these families, many of whom were forced to leave their farms and find other sources of income.