答：Off（你错字了） the top of one's head是美国人经常用的一个习惯用语。它的意思 是：没有经过仔细考虑或仔细计算。do sth.off the top of one's head. 毫无准备地干什么事情http://www.freexinwen.com/chinese/eng/wi/lesson257.asphttp://www.google.com/search?num=50&hl=zh-CN&newwindow=1&q=of+the+top+of+one%27s+head&btnG=%E6%90%9C%E7%B4%A2&lr=参考资料：美国习惯用语 已赞过已踩过<
不是of the top of one's head而应该是：off the top of one's headmeans:Without much thought or calculationFrom Ansears.com:http://www.answers.com/topic/off-the-top-of-one-s-headIn an impromptu way, without much thought, as in Off the top of my head I'd say we'll double our profits in a year. This idiom suggests one has not used the inside of one's head before making some statement. [Mid-1900s]意思是，（表示说话）没有经过更多的思考和考虑（武断；或脱口而出；或即兴）参考资料：http://www.answers.com/topic/off-the-top-of-one-s-head 已赞过已踩过<
