Each ship having an inert gas system must have a portable instruments to measure concentrations of hydrocarbon vapor in inert atmospheres and also to measure ______.
【简答题】分娩是指A. A.胎儿先露部随着骨盆各平面的不同形态,被动地进行一系列的适应性转动,以其最小径线通过产道的全过程 B. B.胎头双顶径进入骨盆入口平面,其颅骨最低点接近或达到坐骨棘水平 C. · C.妊娠满28周及以后的胎儿及其附属物,从临产发动至从母体全部娩出的过程 D. · D.宫缩时胎头露出阴道口,间歇时又缩回