四重

The nth order perturbation corresponds to the nth order scatterings and reflections between the head and torso, therefore, for the conditions of the snowman model, the effects of the earlier three scatterings and reflections on HRTFs are important, and the contributions of the fourth-order and higher-order ones are neglectable.

由于 n 阶微扰在物理上是和头部和躯干之间的 n 重散射相对应的，因而本文的结果表明，在雪人模型的条件下，头部和躯干的前三阶多重散射对 HRTF 是重要的，四阶及以上散射可以忽略。

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。