Заполните пропуски глаголом "to have" или "to be" в соответствующем времени.
1. A contaminated object ... one that contains bacteria.
2. Bacteria ... found in various parts the body.
3. The presence of bacteria does not mean necessarily that a disease process ... been established.
4. A strain that ... reduced virulence is said to be attenuated.
5. Man and animals ... several defense mechanisms for destroying invading bacteria.