"自陈尝在秦王幕府翻译"isnotacompletesentenceanditmayhaveseveralinterpretations.Onepossibleinterpretationis:自陈(zìchén)-tointroduceoneselfortoexplainoneself尝在(chángzài)-usedtoindicatepastexperienceorpreviousresid
"自陈尝在秦王幕府翻译" is not a complete sentence and it may have several interpretations. One possible interpretation is:
自陈 (zì chén) - to introduce oneself or to explain oneself
尝在 (cháng zài) - used to indicate past experience or previous residence
秦王幕府 (qín wáng mù fǔ) - the Qin king's court or Qin dynasty's royal court
So the sentence may mean "Introducing oneself as having previous experience/residence in the Qin king's court."