The findings of a new survey have American professors talking about the good old days—when A's were a lot tougher to earn． Sites like RateMyProfessors．com make it easy for students to find a class taught by a professor who is known as an 'easy grader'．A recent survey by Kaplan Test Prep found that 46 percent of the more than 1,200 students polled admitted to using the site for just such a purpose． 'Our research shows that many of today's college students are looking at multiple factors when picking out courses: overall teacher quality that will result in a good learning experience, but also instructors who don't like to award a lot of C's and D's,' said Jeff Olson, vice president of research at Kaplan Test Prep． 'While it makes sense that students would choose kinder graders, it also helps explain the recent popularity of grade inflation（膨胀）．' Grade inflation is seen by many professors as poisoning the learning environment．Some, like former Duke University professor Stuart Rojstaczer, are righting it head-on． On his website, Gradelnflation．com, he releases an annual list of schools where grade inflation is the worst． This year, he decided to name the schools where grades were inflated the least．He praised, for example, Princeton University, as well as Purdue University, where the average GPA has remained around 2．8 for over 30 years． 'Purdue doesn't even seem to know that grade inflation exists in the US,' Rojstaczer says．'Ignorance is bliss（极大的幸福）．' 68．From the passage we may know that Kaplan Test Prep is most probably _____ A．an institute             B．a professor C．a vice president        D．a course 69．Grade inflation is spreading because _____． A．it's poisoning the learning environment B．instructors intend to improve their overall teaching quality C．many instructors adapt to the students' expectations D．students get easy access to sites like RateMyProfessors．com 70．The passage suggests that _____． A．universities will employ hard graders B．if we want to be happy, we should be ignorant C．A's are becoming easy to earn at most US universities D．professors and instructors should give students higher grades 71．The writer tends to _____． A．favor easy graders                B．see grade inflation as unavoidable C．oppose Kaplan Test Prep         D．miss the days when A's were hard to earn