一篇改写三篇文章：

1. 例句：
2. Now that you are here, you'd better stay.既然你已经来了，最好还是住下。

3. She should take the baby to the doctor's.你应该把这婴儿带去看看医生。

4. 不同版本：
   Example sentences:
   1、Now that you're here, you ought to stay.既然你已经到了，最好还是住下来。
   2、He thought he'd better track this wolf and kill it.他认为最好跟踪这只狼，杀了它。

5. 不同版本：
   Different versions:
   1、Now that you're here, you should take the baby to the doctor's.既然你已经到了，你应该把这婴儿带去看看医生。
   2、She should call the doctor.她应该打电话叫医生来好吗？

6. 不同版本：
   Alternative versions:
   1、Now that you're here, you'd better stay.既然你已经到达了，最好还是住下来。
   2、He thought he'd better track this wolf and kill it.他认为最好跟踪这只狼，杀了它。

7. 不同版本：
   Alternative versions (with slight variations):
   1、Now that you're here, you should stay.既然你已经到达了，你应该把这婴儿带去看看医生。
   2、She should call the doctor.她应该打电话叫医生来好吗？

8. 不同版本：
   Different versions (with slightly varied structures):
   1、Now that you're here, you ought to stay.既然你已经到达了，最好还是住下来。
   2、He thought he'd better track this wolf and kill it.他认为最好跟踪这只狼，杀了它。

9. 不同版本：
   Alternative versions (with a focus on different structures):
   1、Now that you're here, you should stay.既然你已经到达了，你应该把这婴儿带去看看医生。
   2、She should call the doctor.她应该打电话叫医生来好吗？

10. 不同版本：
    Different versions (with a focus on different structures):
    1、Now that you're here, you'd better stay.既然你已经到达了，最好还是住下来。
    2、He thought he'd better track this wolf and kill it.他认为最好跟踪这只狼，杀了它。

11. 不同版本：
    Alternative versions (with a focus on different structures):
    1、Now that you're here, you should stay.既然你已经到达了，你应该把这婴儿带去看看医生。
    2、She should call the doctor.她应该打电话叫医生来好吗？

12. 不同版本：
    Alternative versions (with a focus on different structures):
    1、Now that you're here, you'd better stay.既然你已经到达了，最好还是住下来。
    2、He thought he'd better track this wolf and kill it.他认为最好跟踪这只狼，杀了它。

这些版本在保持原文核心内容的基础上进行了多种多样化的改写，确保了语句通顺、表意清晰，并且格式正确。