21.   When opportunity knocked in Massachusetts, he ran home to Belmont.

22.   When opportunity knocks for any of the small-time operators he writes about, it tends to bring mind-boggling complications even to the simplest and most reasonable of illegal schemes.

23.   When opportunity knocks you can either ignore it or go for it.

24.   When opportunity knocks, Karey Barker is usually ready to open the door.

25.   While others wait for opportunity to knock, Brad did his own knocking.

26.   Indeed, opportunity knocks at strange hours.

27.   It had more to do with opportunity knocking.

28.   Microsoft executives accused Lieven of negotiating in the news media but showed respect for this man who, like Bill Gates, dropped out of college when opportunity knocked.

29.   Still, confidence could return once people begin to realize that opportunity could knock as a result of the steep decline.