4. Rewrite the sentences in the Passive, as in the example. They haven't served the table yet. The table hasn't been served yet.

1. The walls haven't been painted yet. 2. Pictures and posters in the living room still haven't been hung. 3. The origin of the Universe won't be explained very soon. 4. That exhibition won't be opened in June. 5. The bridge hadn't been built by May.