单项选择题
A.被控量允许变化范围太小 B.上限值太大 C.被控量允许变化范围太大 D.上限值太小
A.使给定弹簧预紧力减小 B.使给定弹簧预紧力增大 C.使幅差弹簧预紧力增大 D.使幅差弹簧预紧力减小
A.0,0.07MPa B.0,0.25MPa C.0.07MPa,0.25MPa D.0.25MPa,0.5MPa