Put the verbs in brackets into the correct tense or form. 1. If we __________ (not stop) cutting down so many trees, we’ll endanger our oxygen supply. 2. Last year Mr. Johnson _____________ (teach) us Robotics. 3. My sister is really busy – she _____________ (study) for the exam. 4. In the future, robots _____________ (do) things that people can’t do or don’t want to do. 5. Mark _____________ (be) to Sa Pa twice. The first time _____________ (be) more than ten years ago. 6. How often _____________ (you/ do) household chores? ~ Every day. 7. Twenty years ago, most people around the world _____________ (not know) what the Internet was. 8. If we dump all sorts of chemicals into rivers, we _____________ (not be able to) swim in them in the future.