why don't you get her a scarf for her birthday?中为什么用for

get sth for 。for介词 prep。1。为,为了They fought for national independence。他们为民族独立而战。This letter is for you。这是你的信。2。代替;代表We used boxes for chairs。我们用箱子当椅子坐。3。因为,由于I am sorry for what I said to you。我后悔不该对你讲那些话。4。在(指定时间)The meeting is arranged for 9 o'clock。会议安排在九点钟。5。(表示时间、距离等)达,计You can see for miles from the roof。你站在屋顶上可以看到数英里之外。6。对于,关于;在。。。方面I am too old for the job。我年纪太大,做不了这工作。7。为得到,为赢得He sent the waiter for a packet of cigarettes。他让侍者去拿一盒香烟。8。以。。。为代价;以。。。交换He sold his car for 500 dollars。他以五百元把车卖了。9。当作,作为Do you take me for a millionaire?你是不是把我当百万富翁?10。赞成;支持;倾向于Are you for the government or against it?你是支持还是反对政府?11。朝。。。方向去;往,向He left for Taipei。他出发去台北。12。就。。。而言She is sophisticated for her age。就年龄而言她是世故了一点。