a fly on the wall 英[ə flai ɔn ðə wɔ:l] 美[e flai ɑn ði wɔl] [词典] 隐蔽的或不引人注意的旁观者; [例句]What I'd give to be a fly on the wall when Davis finds out what's happened to his precious cargo.我多么希望能够看到戴维斯发现他珍贵的货物出事时的样子啊。