Use Present Perfect.

1. We _______________ (talk) about the environment in our English class this week.

2. The air _________(get) worse and worse in the last twenty years.

3. That factory ______________ (pollute) the river.

4. I have read (read) your book several times.

5. You ________________ (break) the glass again.

6. We _______________ (see) him before.

7. I _____________ (have) a snake