out of the blue 意想不到
I got a call from my old classmate out of the blue.
我突然接到一个老同学的电话。
I just got a big raise out of the blue.
我突然得到了加薪。
till one is blue in the face 唇干舌燥；直至脸色发青
You can argue till you're blue in the face; I still won't go.
就算你说到唇干舌燥，我也不会去。
You can memorize grammer rules till you are blue in the face, but it won't improve your spoken English.
即使你竭尽所能地记忆语法规则，还是不能提高你的英语口语。
once in a blue moon 千载难逢，极少，偶尔
He cooks only once in a blue moon.
他极少下厨。
How could you miss such a once-in-a-blue-moon chance?
你怎么能错过这个千载难逢的机会呢？
[ 本帖最后由 Sylvia_scj 于 2008-2-27 02:34 PM 编辑 ]
