Of all the goals of the education reform. movement, none is more difficult than developing

Of all the goals of the education reform. movement, none is more difficult than developing an objective method to assess teachers. Studies show that over time, test scores do not provide a【C1】______ means of separating good from bad instructors. Test scores are an【C2】______ indicator of quality because too many factors outside of the teachers control can influence student【C3】______ from year to year—or even from classroom to classroom during the same year. Often, more than half of those teachers【C4】______ as the poorest performers one year will be judged average or above average the next, and the results are【C5】______ as bad for teachers with【C6】______ classes during the same year. 【C7】______, theres a far more direct approach: measuring the amount of【C8】______ a teacher spends delivering relevant instruction—【C9】______, how much teaching a teacher actually gets done in a school day. This is hardly a new【C10】______. Thirty years ago two studies using this approach found that some teachers were able to deliver【C11】______ 14 more weeks a year of relevant instruction than their less efficient【C12】______. There was no【C13】______ to their success: it was obvious that the efficient teachers【C14】______ strictly to the curriculum, maintained stern discipline and【C15】______ non-instructional activities, like【C16】______ unessential classroom business when they【C17】______ focused on the curriculum. And both studies found that the teachers who【C18】______ more were also the teachers who【C19】______ students who performed well on【C20】______ tests.

【C1】

A．persistent

B．consistent

C．continuous

D．useful

请帮忙给出正确答案和分析，谢谢！