过期杂志的英文：
back number
- All the out-dated magazines are half-price.
过期杂志一律半价。
n. 后面，背面，反面；背，背部；靠背；后卫
v. 支持；后退，倒退；背书；下赌注于
adj. 背部的；后面的；过去的；拖欠的.
adv. 以前；向后地；来回地；上溯
- Stand back to back!
背靠背站好！ - They are on the back of the menu.
它们在菜单背面。 - Our seats on the train were back to back.
我们在火车上的坐位是背靠背的。 - It happened far back in the past.
这事发生在久远的过去。 - the back of a Chinese robe or jacket
后襟
n. 数；号码；算数
v. 给…编号；计算，数
- The number was fifty.
该数字为五十。 - There is safety in numbers
人多势众 - It was an irrational number.
这是一个无理数。 - Which number on the card is a prime number?
在卡片上哪一个数字是最初的数字？ - The number raised to the logarithm of a designated number in order to produce that designated number.
被升到指定数字的对数上的数量,是为了得到那被指定的数目。