a window of opportunity 就是机遇之窗的意思，指可以做某事的一个短暂时机或可能。
- I've got a window of opportunity to talk to my boss about a pay rise tomorrow.
- Meet me in reception - there might be a window of opportunity for me to let you into the concert!
- Sometimes a problem can actually be a window of opportunity.
值得注意的是，go out (of) the window 的意思是什么事情已经过去了，来不及了、不可能了。
- My computer crashed yesterday, so any chance of finishing my work has gone out (of) the window.
