Related Clues:

• Had down cold
• Had dealings with
• Had all the answers
• Had down pat
• Was certain of
• Apprehended
• Certified
• Had met before
• Was acquainted with
• Appreciated
• Was privy to
• "... Yorick! I __ him, Horatio": Hamlet
• ''I ___ it!''
• Double-checked
• Had no doubt