Answer:
1. We could fly but also we could go by train.
2. she will have to study hard and she will have to concentrate to do well on the exam.
3. Jack is not here but Tom is in another city.
4. The speaker will not confirm the story nor deny the story.
5. Pneumonia is a dangerous disease but also smallpox is a dangerous illness.
6. Fred loves traveling also Jane wants to go around the world.
7. It might or snow tomorrow.
8. Playing tennis is good for your heart and is good for your health.