1 The first step, eliminating particles, can be done with a clean room.
请问老师,eliminating particles是看作非限制性分词短语,还是说动名词短语做the first step的同位语?动名词短语可以做同位语吗,有这种用法吗?根据意思,我觉得倾向于同位语
2 The second step, background radiation, can be done by going underground.
这里background radiation做the second step的同位语,对吗?