used in rhetorical questions for emphasis or to express doubt

once; ever in the past; indicates that an action has previously occurred or a state has existed; often used as a formal or written shorthand for 曾经 céng​jīng

Used to emphasize a point, express a strong contrast to expectation, or add force to a question or command; often used with 了 le, 呢 ne, or 啦 la at the end of the sentence.

(literary) unexpectedly; to one's surprise; as it turns out