消防应急灯具的应急转换时间应不大于_s。
A.15
B.5
C.2.5
D.0.25
参考答案:B
____ by taking part in practice can the young people be toughened and hardened into steel
A.Still
B.Just
C.Only
D.Yet
同时履行抗辩权在性质上属于().
A.法定权利
B.约定权利
C.延期抗辩权
D.永久抗辩权