doorstop的复数形式怎么拼写？

He used a large book as a doorstop.他用一本厚书控制住门.The door was held open by a doorstop.那门用了门碰头,一直开著....

doorstop的音标：doorstop的英式发音音标为：['dɔ:stɒp]doorstop的美式发音音标为：['dɔrstɑp]...

n.制止门过开之物（如钩环）...