When you search words/phrases in Concord/Cluster/Collocation, some characters have special meaning.  The following characters are used for wildcard search.

• *  (asterisk)
  
  * functions as a wildcard of 0 or more character string.  If used independently, it is treated as any one word or zero word.  If attached to a string, it is treated as a part of that string (0 or more characters).  So
  
  in * context returns in context, in a context, in the context, etc.
  
  context* returns context, contexts, contextual, etc.
  
  
• !  (exclamation mark)
  
  ! functions as a wildcard of 1 character, so
  
  ma!e returns made, make, male, mate, etc.
  
  
• ?  (question mark)
  
  ? functions as a wildcard of 1 or more character string.  If used independently, it is treated as any one word.  If attached to a string, it is treated as a part of that string (1 or more characters).  So
  
  in ? context returns in a context, in the context, etc., but not in context
  
  context? returns contexts, contextual, etc. but not context
  
  
• (A|B)
  
  (A|B) functions as A or B wildcard, so
  
  it (is|was) interesting returns it is interesting and it was interesting
  
  
• /  (slash)
  
  / functions as a separator of search queries, which means search strings separated by / are treated as two different queries, so
  
  result/finding returns result and finding
  
  it is/was interesting returns it is and was interesting
  

You can combine these wildcard characters to search complex strings:

    it (is|was|should be) * * that 

    returned the following clusters in Brown corpus

    it is also found that, it is believed that, it is that, it should be noted that, it should be painfully obvious that, it was a face that, it was evident that, it was that, etc.