FEw mAthEmAtiCiAns ArE ------- thEir FuturEs on FinDing Any suCh prooF; instEAD, thEir EFForts ArE FoCusED on FinDing gooD, But not -------, solutions For most CAsEs, A FiElD oF stuDy Aptly known As ApproximAtion thEory.
A．BEtting … pErFECt
B．DEvEloping … ConvEniEnt
C．pinning … suBstAnDArD
D．DEstroying … ExACt
E．(E) EstABlishing … vAguE