No.4 will give you very useful word. When you need something , all you have to say is this word "Onegaisimasu" means "Please".

When you need to ask something , or favor , this word is the perfect fit.

You can see this script as an example.

Nanika onomimonoha? (Would you care for something to drink?)

Kofi onegaisimasu (Coffee Please)

Hai douzo (Here you go.)

Arigatou (Thanks)

Sentences consist of Something plus please is probably the most convenient word to ask favor. You can use this , when you need drink , when you need food , when you need to ask favor.

**** onegaisimasu (**** please)