plough的现在分词怎么变化

例句：

The field had been ploughed and planted with corn.

这块地已犁过并种上了玉米。

There was not one inch of soil that was not under the plough.

没有一寸土地未被开垦成耕地。

The more ploughing and weeding, the better the crop.

一分耕耘，一分收获。