1. The UPC is printed by the manufacturer on each grocery item — a set of thin and thick vertical stripes accompanied by a series of numbers under the stripes and a zero, centered to the left of them.
    条形码由厂家印在每一食品上——这是一组粗细不同、垂直排列的线条，线条下方有一组数字，左边有一个“0”字。

2. As the grocery items moves along the conveyor belt, the checker passes each item over a glass plate in the counter top, making sure that the UPC symbols can be read by the laser beam under the glass.
    食品杂货经传送带传到收款员跟前，收款员随即将每一物品搁在柜台上的一块玻璃板上一扫，好使板下的扫描机阅读条形码。

3. Since few shoppers know what the UPC means, there is a sign on the shelf giving the name of the product, its weight and its price.
    因为顾客几乎不知道条形码所指代的东西，所以货架上一般有一个小牌，写着商品的名称、重量及价格。

4. Let´s begin with what the shopper sees first, the Universal Products Code (UPC) symbol.
    我们先来讲讲顾客首先会注意到的东西——通用条形码。