未设防

In that age of violence and disorder, the first use made by a serf of any small provision which he had been able to accumulate,was to buy his freedom and withdraw himself to some town or fortified village, which had remained undestroyed from the time of the Roman dominion

在这个暴力和混乱的年代里，能积聚一点点存粮的农奴，要做的第一件事，就是赎回自由并迁移到某个从罗马统治时期保留下来而未被毁坏的城镇或设防村庄

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。