Can (Informal request)
- Can I borrow your pen, please?
- Can you close the door, please?
- Can he come with us, please?
- Can they help me, please?
Could (Formal polite request)
- Could I have some water, please?
- Could she help me with my homework, please?
- Could you open the window, please?
- Could we go to the park, please?
Ответ: See answers above