Migration and transformation of agricultural non-point source pollutants in drainage ditches .
农业非点源污染物在排水沟渠中的迁移转化研究进展。
All the cylinders can be blocked when the vehicle overcomes ditches that are up to 4 m wide .
当车辆需要通过宽4米以上的水沟时，这些气缸可以都被塞住。
He made ditches in the fields to draw off the water .
他在田里挖了沟以便排水。
They were kept busy digging ditches .
他们一刻不停地忙于挖沟。
These are proving very useful because of their portability and also their downward attack trajectory , which enables them to be effective against enemy personnel hiding behind cover or in ditches .
