One cause of this attitude students have can be represented by the fact _____ young teachers don't

know how to impose their respect among their students. [ ]

A. which

B. that

C. why

D. /

设备维修拆卸后清洗机件一般均用煤油，但精密件或滚动轴承用煤油清洗后必须再用汽油清洗一次。