Goodness/God/Heaven/Christ knows 
 
used to mean "I don't know" or to emphasize a statement. Some people may find this use offensive.
(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)
 
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!