滤波器中，一般规定幅频特性值等于1.414A时所对应的频率称为截止频率。（）
参考答案：错
We should consider the students' request _____ the school library provide more books on popular science. [ ]
A. that
B. when
C. which
D. where
大家一致公认，矿石的（）提高1%，焦比降低2%，产量提高3%。
