奴隶制的英文：
helotism

An underground railroad
(反对奴隶制者)帮助南方奴隶潜逃到北方或加拿大的秘密组织

To abolish slavery
废除奴隶制

The abolition of slavery
废止奴隶制

Slavery was done away with a long time ago.
奴隶制早已废除了。

Slavery was done away with a long time ago
奴隶制早已废除了。

Throw off the yoke of slavery
摆脱奴隶制的枷锁

slavery plantation in the United States of America
美国种植园奴隶制

Slavery was once socially sanctioned.
奴隶制曾经为社会所认可。

His first publication was a forcible article against slavery
他的处女作是一篇反对奴隶制的令人信服的论文。

free soil
[美]无奴隶制的地方;自由土地,自由地区