on〔under〕 oath
在法庭上宣过誓要说实话sworn to tell the truth in court of law
The judge reminded the witness that he was still under oath.法官提醒证人,他已发过誓要说实话。

They swore an oath of loyalty to the country.他们宣誓要报效祖国。
He hurled a few oaths at his wife.他骂了妻子几句。

oath, pledge
这两个词的共同意思是“誓言”。
1.pledge指“诺言”或“保证”,是正式用语; oath指一种正式的许诺或保证,含有如违背誓言便要为其后果负责之意。
2.pledge尤其用于指政府或政党的誓约、保证; oath则多用于法庭上的宣誓。

［同义词］   curse word, swearing, vow
［反义词］   blessing, invocation, prayer
［词源］＜古英语ath(誓言)