Can I have a few / a little onions , please . a few a little

The correct sentence is: Can I have a few onions, please?

Few is used with countable nouns

Little is used with uncontable nouns(when you're talking about the quantity)

a - have been

b - have not had. saw 

a - was

b - left. came. have found/ 

greg proposed to have some chocolate

cristina proposed some more juice to sandy

dad adviced to gabi not to drink cold water

mum asked nastea to put the pie into the oven