1. Give us a ring soon. (Formal)
I would like to call you soon.
2. It would be great if you could help me. (Informal)
Please, could you help me?
3. I am writing to ask for some information. (Formal)
I want some information, please.
4. I'd really like to do your course. (Informal)
I would like to enroll in your course.
Ответ: I would like to call you soon; Please, could you help me?; I want some information, please; I would like to enroll in your course.