or，er在英语中是r音节(ar,er,ir,or,ur)，在一个动词后面加ar,er,or这些r音节可以构成名词，所以ar,er,or这些r音节是名词后缀，如：

beg →beggar

work→worker

teach→teacher

play→player

write→writer

invent→ inventor

collect →collector

act→ actor

edit→ editor

translate→ translator

visit→ visitor

detect→ detector

lnfect →infector

sail→sailor

conduct→ conductor

tail→tailor