内机有噪音，非风声，非热胀冷缩声，而是一种嗡嗡声，在不工作时也有，何故？
参考答案：
变压器的声音。
Nine in ten parents said there were significant differences in their approach to educating their
children compared with ________ of their parents. [ ]
A. those
B. one
C. both
D. that
依出版形式划分，期刊可分哪几种？
ents said there were significant differences in their approach to educating their