Which sentence is punctuated correctly?
1. Scientists know that Earth has been impacted by large asteroids in the past however; what happens if a major asteroid hits Earth now?
2. Scientists know that Earth has been impacted by large asteroids in the past, however what happens if a major asteroid hits Earth now?
3. Scientists know that Earth has been impacted by large asteroids in the past however what happens if a major asteroid hits Earth now?
4. Scientists know that Earth has been impacted by large asteroids in the past; however, what happens if a major asteroid hits Earth now?
1 answer
The fourth sentence is punctuated correctly: "Scientists know that Earth has been impacted by large asteroids in the past; however, what happens if a major asteroid hits Earth now?"