for a girl和to a girl的意思相同,意思都是给一个女孩.
for a girl的例句是I'm buying this gift for a girl.
意思是我买这个礼物是送给一个女孩的.
to a girl的例句是I'm sending a message to a girl.
意思是我在给一个女孩发短信.
as a girl的意思是作为一个女孩,用于第一人称(first person)
例句是As a girl,I don't like sports.
意思是作为一个女孩,我不喜欢运动.