In Houston, a controversial education reform measure allows teachers to be fired based on their students’ test scores. Some parents back the policy, but teacher unions have reservations. Reform advocates say school districts should improve teacher quality in part by using the "value added" data. Dozens of districts, including Houston’s, have already. (36) the concept into "pay for performance" systems. Education leaders in New York City and the District of Columbia are moving toward linking it to tenure (任期) or dismissals. But none has gone (37) as boldly as the Texas district. "The biggest tension is: How much do you rely upon (38) statistical information from test scores, and how much do you rely on other measures of teacher performance", says Eric Hanushek, a senior fellow at Stanford’s Hoover Institution in California. A number of parents backed the Houston decision at a packed February board meeting. But the local teacher union is planning a (39) challenge, claiming, among other concerns, that the formula is not public and leaves teachers in the (40) about how they’re judged. The district defends it as a tool to help principals (41) that each classroom has an effective teacher. No one has been let go yet under the new policy, but at the end of the school year, the data could be cited as one criterion for not (42) a teacher’s contract. The controversy highlights a (43) debate over how to improve teacher evaluations. For all the potential flaws, linking teacher evaluations to student achievement data is a move in the right direction, says Kate Walsh, president of the National Council on Teacher Quality in Washington. Under the status quo (现状), she says, teachers tend to be fired only if they are (44) or break the law. Studies in a sample of districts across the United States have found that less than one percent of teachers earn an unsatisfactory (45) on their evaluations. A. dark I. legal B. abusive J. rating C. classification K. ensure D. incorporated L. ahead E. signing M. assure F. reasonable N. subjective G. objective O. renewing H. broader