Put the verbs in brackets into the correct verb form.
      1. I (have)                         dinner when his friend called.
      2. Joan (travel)                              around the world.
      3. We (not begin)                          to study for the test yet.
      4. Don’t get on a bus while it (run)                                  .
      5. I (invite)                                    them to my birthday party yesterday, however, they (not come)                   .
      6. Look! Somebody (clean)                                  the room.