At an angle of loll，the righting arm (GZ) is（）.
A. maximum
B. negative
C. positive，but reflexive
D. zero
In an auxiliary diesel engine, the reason for knurling the piston skirt is to（）
A. improve skirt lubrication
B. allow for expansion
C. transmit forces evenly
D. improve the piston seal
ERP系统中的采购可以实现（）采购。
A. 订货点采购
B. 电子商务采购
C. 供应链采购
D. MRP采购
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