问题：
[单选题]单层厂房吊车梁吊装时，必须在柱杯口第一次浇筑的混凝土达到以下何值时，才能拔去临时固定的楔子浇筑第二次混凝土？【 】
A、设计强度等级的15%
B、设计强度等级的25%
C、设计强度等级的50%
D、设计强度等级的75%
参考答案：
B
相关内容
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- ● Mainly eat 3 or 4 partly cloudy to overcat occaional rain（）lowly outh moderate or good.
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- ● Should any cae or upected cae of quarantinable dieae，or any cae of eruptive dieae or any death be dicovered，the local Quarantine Officer mut be（）immediately.
- ● Damage to cargo caued by fume or vapor from liquid,gae, or olid i known a（）.
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- ● （）mean any peron by whom or in whoe name or on whoe behalf a contract of carriage of good by ea ha been concluded with a carrier，or any peron by whom or in whoe name or on whoe behalf the good are actually delivered to the carrier in relation to the contract of carriage of good by ea.
- ● If he i a common carrier，he i abolutely reponible to the owner of the good carried （）any lo or damage to them unle caued by an Act of God or the Queen’ enemie，or the inherent vice in the good themelve，or the negligence of the owner of the good，or a general average acrifice.
- ● 系统中雷达状态包括Unknown、Operational（or ON）、Failed（or OFF）、Detached。
- ● Owner are to be reponible for lo of or damage to the good or delay in delivery of the good only in cae the lo，damage or delay ha been caued by the improper or negligent towage of the good．Thi mean that（）.
- ● The carrier i liable for lo of or damage to the good or delay in delivery caued by fire，（）the claimant prove that the fire aroe from fault or neglect on the part of the carrier，hi ervant or agent.
- ● Shutdown price（or point，or rule） 停业价格（或停业点、停业原则）
