Touch wood 但愿走好运
It is customary to place your hand on something wooden when saying the phrase ‘touch wood’ to try and ward off bad luck. If there’s no wood available, some people put their hand on their head! Although opinion about the origin of the phrase differs, some people believe it was linked to mythology of trees, which were thought to possess spirits. By knocking or touching the wood of the trees, the spirits would know you were there and would offer you good fortune.
英国人有时也迷信，比如 touch wood 就是但愿走好运的意思。
I've done all of the preparation for the exam, so nothing can go wrong now – touch wood!
I've never broken any bones, touch wood!
The train is currently on time so we shouldn’t miss our flight, touch wood.
短语 touch-and-go 通常用来形容某种形式或某人的状态很不稳定。
My grandfather had an operation last week. It was touch-and-go at one point, but he's fully recovered now.