Verified answer

Answer:

Would

I would like to have a formal conversation with your parents.

Would it be okay if I joined with you team?

would you mind sending this letter to her?

Could

I could run better when I was younger.

Answer:

1.I can sleeping six hours tonight.

2.I couldn't worked last night

3.What will it be like, living in the 21st century

4.We'll will all be dead in a hundred years

5.Stop crying! It won't make things any butter you know