11.   State accounting societies forbid firms to accept fees based on the successful completion of a particular deal or some other contingency basis.

12.   The firm would be paid on a contingency basis, receiving a percentage of the funds it recovers.

13.   The lawyers took the case on a contingency basis, and stand to share in the judgment.

14.   Zhou works on a contingency basis.

15.   He was willing to take their case on a contingency basis, and they filed their own patent for the drug as a treatment for baldness.