多选题 As head of the National Education Association in 1965-66, Elizabeth Duncan Koontz advocated higher salaries for teachers because she believed that the more ______ teaching is, the greater its attraction for highly qualified people.
【正确答案】 D、F
【答案解析】[解析] ● because说明前后同义重复。
● 空格与higher salaries(更高的薪水)同义重复。
● precarious不稳定的，dubious不稳定的，controversial有争议的，lucrative有利的，productive丰富的，profitable有利的。答案选DF。
● 注：这里precarious和dubious是干扰项，同表示“不稳定的”。