设某刨床刨削时作匀速运动，它的切削速度v=0.75m/s，此时切削力为31kN，若机械效率η=0.78，试求驱动刨床工作台所需电动机的功率。
You execute the following command to audit database activities： SQL> AUDIT DROP ANY TABLE BY scott BY SESSION WHENEVER SUCCESSFUL； What is the effect of this command（）
A. One audit record is created for every successful DROP TABLE command executed in the session of SCOT
B. One audit record is generated for the session when SCOTT grants the DROP ANY TABLE privilege to otherusers.
C. One audit record is created for the whole session if user SCOTT successfully drops one or more tables inhis session.
D. One audit record is created for every session of any other user in which a table owned by SCOTT isdropped successfully.
E. One audit record is created for every successful DROP TABLE command executed by any user to drop Tables owned by SCOTT
对生产工艺过程和保安条件不允许自起动的高压电动机，应设置低电压保护，对较为重要的电动机（额定电压3Kv、6Kv）电压继电器按30%~50%额定电压，动作时间6~10s来整定。
A. 正确
B. 错误
1个月男婴，生后至今经常出现呕吐、腹胀，便秘明显，有时持续1周以上不能自行排便，需使用开塞露才能排出，便秘期间腹胀明显，可见肠型并触及充满粪块的结肠袢，其可能的诊断是（）
A. 生理性腹泻
B. 先天性巨结肠
C. 急性坏死性小肠结肠炎
D. 肠套叠
E. 病毒性肠炎
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