她出于原则不穿皮草。

She doesn't wear fur ___on ___principle.

他们出于原则从不喝酒，但却买了几瓶酒喝醉了。

They, ___on ___principle, never drank alcohol, but they bought some bottles of wine and got drunk.

他出于原则拒绝签署这份文件。

He refused to sign the document ___on ___principle.