安装离心泵的机械密封时，动环上的凹槽要与压盖上的防转销对正。（）
参考答案：错
She is a bit shy and _______ stand up and answer the teacher's questions. [ ]
A. dares not
B. doesn't dare
C. dare not to
D. dares not to
古代被誉为诗鬼的是谁？
