Here are the completed sentences:

1. It is over two years since they left their homeland. (They haven't **returned since**.)
2. "How many cars are there in front of your house, Mai?" I said (I asked **Mai how many cars were** in front of her house.)
3. No one introduced me to newcomers in the festival. (I **wasn't introduced to** newcomers in the festival.)
4. The food was too bad for the children to eat. (The food was so **bad that the children couldn't eat it.**)
5. It's no use persuading her to join in that activity. (There is no **point in persuading her to join** in that activity.)

Feel free to ask if you need further assistance!