11.   Frequent flyer miles are an especially successful devise for increasing lock-in, a subtle form of volume discount.

12.   Further, because Internet users need to type everything they wish to communicate, they have developed extremely subtle forms of written communication.

13.   He detailed several changes he had made to encourage the flow of ideas within the agency and to protect whistle-blowers from even subtle forms of retaliation.

14.   He spoke to the camera as if it were a beautiful woman he was trying to charm with subtle forms of verbal flattery and sexy body language.

15.   His long career in the Senate has helped him develop a far more subtle form of communication.

16.   Instead, coaches and athletes say they are increasingly invoking the law to challenge more subtle forms of discrimination.

17.   Instead, coaches and athletes say they are increasingly using the law to challenge more subtle forms of discrimination.

18.   Klaus, the consultant, says more subtle forms of discrimination are widespread.

19.   Maybe the world has gotten too complex, too predictably shadowy, to offer much shelter anymore for such a subtle literary form.

20.   One more subtle form of sexism contributes to lower salaries for women, Sullivan said.