as plain as the nose on your face	- to be very obvious
as keen as mustard	to be very eager
as fit as a fiddle	in very good health
as gentle as a lamb	very gentle
as light as a feather	to be very light in weight
as miserable as sin	być nieszczęśliwym
as old as the hills	very old
as dull as ditchwater	very uninteresting
as good as gold	very well behaved
as pleased as Punch	delighted; very pleased