library card
对于每个拥有借书卡(library card)的人都有一个 key。对于这个 key,其对应的 value 是其借书的数量,如果从没有借过,其 值为 undef。
borrower's card
... borrower 借用人 borrower's card 借书卡 borsch 罗宋汤 ...
admission card
... delivery desk 借书台 admission card 借书卡 closed reserved 只读不借 ...
library card/admission card
... charge out把...借出来 library card/admission card借书卡 date slip/deadline/date of expiry期限 ...