Goodness/God/Heaven/Christ knows idiom informal
（表示不知道或加强语气）天知道（有些人认为此种表达具冒犯意）
used to mean "I don't know" or to emphasize a statement. Some people may find this use offensive.
God only knows what'll happen next! 只有老天爷知道接下来会发生什么！
Take your shirt off - Heaven knows it's hot enough today! 把衬衫脱了——今天可够热的！