是一种较为现代化的地下管道施工方法，借助于主顶油缸及管道中继间的顶推力，使工具管或掘进机从工作井内穿过土层，并一直推到接收坑内后吊起。
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是盾构施工的主要装配构件，是隧道的最内层屏障，承担着抵抗土层压力、地下水压力以及一些特殊荷载的作用。
Which type of infection does not belong to nosocomial infection?
A. The doctors acquire the pathogens from their patients when he examine the patient.
B. The pathogens invade the wound of a worker when he participated inconstruction of a new hospital.
C. The patient's infection was caused by not sterilized surgical scalpels .
D. The newly born baby get infection during delivery.
Which statement is right about endotoxin?
A. It is inactivated by 56℃within 30min,
B. Toxoid can be made from endotoxin,
C. They are LPS produced by G- bacteria,
D. They are best antigens.
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