A new poll shows Gov. Corzine earning poor grades among voters. Voters in the Monmouth University/Gannett New Jersey Poll released yesterday gave the Democratic governor an overall grade of C-. The poll graded Corzine on controlling costs and cutting waste. Corzine’s highest grade was C, which he got in two areas: his level of effort and the public schools. His lowest grade was D for New Jersey’s high cost of living. The poll also shows most New Jerseyans fail to see what, if anything, Corzine has accomplished in nearly four years in office. Corzine’s reelection bid is being challenged by former U.S. Attorney Christopher J. Christie. The telephone poll of 923 people was taken July 9 to 14 and has a margin of error of plus or minus 3.2 percentage points. AP