III. Choose the correct answer in parentheses. 1. Every one of the buildings ( have / has ) a structural problem. 2. Fifteen percent of the money ( are / is ) invested in real estate. 3. A number of messages ( have / has ) been left for the president. 4. The number of lives lost during the Black Death ( are / is ) unbelievable.
1) have / has
2) are / is
3) have / has
4) are / is