I think the main reason why the Great Wall was rebuilt in the fourteenth century is a will to keep out the Mongolian invaders from the north (answer B). It took place during the Ming dynasty which had quite a big problems with the invasions before.
Answer:
In most cases - it is not possible (or desirable), & in few cases cases, it might be possible (or desirable).
Explanation:
Profession is an occupation based on proper formal qualification, training. Eg : Doctors, Lawyers.
They require specialised knowledge (accredited) to practice as a professional. So, involvement in multiple professions is not possible (desirable) in most cases, as it hinders focus & specialised competence (expertise) in single field.
However, in some cases, it might be possible (desirable) if the fields are related. And it also might be need of exposure for the professional. For eg - An economist might be economic consultant & a professional teacher in an education organisation at the same time.
She had been leading us for years, but then she moved away.
This is the correct way to form past perfect progressive of the verb <em>to lead.</em>
