汽轮机危急保安器的整定动作转速宜为额定转速的()。
A.109%~111%
B.108%~110%
C.107%~109%
D.108%~111%
参考答案:A
—Sam, _______?
—Yes, Mum. Do you need my help? [ ]
A. what's today
B. what are you doing
C. are you free now
D. can you help me cook
公安工作既有鲜明的阶级性,又有广泛的社会性。 ( )