金融保险国库券收益计算题某人于1991年3月30日购买1990年国库券,投资成本（成交加上费用）为116元,到期本息为1

两个金融保险的英译汉 不用整句翻
1.Before you or your family can receive benefits,you must have credit for a certain amount of work in covered employment.For 2011,covered employees and the self-employed received one credit(also called a quarter of coverage)for each $1,120 in covered annual earnings.重点说说 credit 咋翻我知道他有学分、信誉、存款的意思.另外for each 针对的是每个人还是每个credit 2.You are currently insured if you have at least six credits out of the last 13 quarters ending with the quarter of death,disability or entitlement to retirement benefits.(请从if开始翻一下) 3.The benefit amounts depend on average monthly indexed earnings and any credits for delayed retirement.(indexed earnings 咋翻)