1. A few minutes later, the dog started to have a stomachache and we had to take him to the hospital.

Question

2. A few minutes later, the dog started to groan lying on the floor, so we had to take him to the hospital.

3. A few minutes later, the dog began to make a strange sound sitting on the floor, and we had to take him to the hospital.

4. A few minutes later, the dog groaned and felt painful,so we had to take him to the hospital.

(Would you check the sentences and correct some errors? Thank you.)

Answer 1

1 and 4 are correct as they are. Don't forget the space after the second comma in #4.

2 and 3 need some slight rephrasing. As they are, 2 reads as if the groan were lying on the floor! 3 reads as if the dog's strange sound were sitting on the floor!! Here's how to fix 2 and 3:

2. A few minutes later, the dog was lying on the floor and started to groan, so we had to take him to the hospital.

3. A few minutes later, the dog was sitting on the floor and began to make a strange sound, so we had to take him to the hospital.