Choose the correct option.

1. After the flood, the town's water ... became contaminated. 2. The prisoner was ... to his cell for one week. 3. Teenagers can find the ... from school to university difficult. 4. Two ... ago, Rome ruled the Mediterranean. 5. The twins ... after being placed in separate classes. 6. The lions ... the horizon in search of food. 7. Cries from the ... of seabirds filled the air. 8. He planted a flag on the ... of the mountain. 9. The snake ... in warning as the boy approached. 10. The marine scientists checked their diving ... last week. 11. By 2050, scientists ... that the polar ice caps will have melted.