双轨巷道乘人车场（）安全措施。
A、必须设信号区间闭锁
B、不须设信号区间闭锁
C、人员上下车过程中，允许其它车辆进入乘车场
参考答案：A
由2-a＞0，得a＞2；______．
All the donated money should be made full use _______the homeless people in Ya'an city of Sichuan province.
A．of helping
B．to help
C．of to help
D．to helping
