题目

下面几何体的截面图可能是圆的是（ ） A . 正方体 B . 圆锥 C . 长方体 D . 棱柱 答案：B5、Bar Code     All the packets you buy in a supermarket carry a bar code．This code is scanned （扫描） by laser light and the brand and product names are given to the customer with the price．The people running the store can keep a continuous check of how many packets of each product and of size are on the shelves．Special supermarket checkouts are needed to read the code．     The code is a mixture of bar and space width．It is printed onto the package and cannot be written by hand． A bar code showing the Australian Product Number （APN） symbol, made up of vertical （直的） stripes and spaces．     The Australian Product Number, which you see in supermarkets, is made up of 13 digits （numbers）．For example: 9300663271733 means: 93 ＝ country code．Australia is 93, New Zealand is 94． 00663 ＝ manufacture's code--all products from this maker have this code number． 27173 ＝ product number and size tells what the product is, and the size of the article． 3 ＝ check digit--from the addition of some previous digits．This check's to make sure that the code has been read correctly． 1．Bar Codes are made up of ________． A．13 equally spaced bars               B．13 numbers matching 13 even bas C．a mixture of bars and space widths     D．a mixture of equal spaced, varying width bars 2．It is NOT possible to ________．     A．have Bar Codes for all supermarket packets     B．make Bar Codes, using more than one zero     C．buy goods using foreign Bar Codes     D．draw your own Bar Codes 3．The following Bar Code informs the supermarket manager that the ________． 9312345678907     A．product has no APN symbol     B．goods came from New Zealand     C．product was produced in Australia     D．particular goods are almost out of date．