题目

浆细胞产生抗体是免疫调节中的重要环节，下列叙述正确的是（）       A．  浆细胞与记忆B细胞膜上的糖蛋白种类有差异       B．  浆细胞与效应T细胞中的遗传信息有明显差异       C．  浆细胞内对抗体进行加工的细胞器中含有DNA       D．  抗体与抗原的特异性结合发在浆细胞的表面 答案：A阅读理解 阅读下面短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。 　　Before you buy a jet printer (喷墨打印机), you'd better decide in advance how much printing you need to do. Then you can print test pages using a variety of printers, a good way to get a quick picture of what a machine can really do. After that, check the specification (说明书) carefully. Here are factors to consider. 　　Resolution: Resolution refers to the number of dots that a printer lays down per inch of paper. Higher - resolution printers theoretically produce more detailed images with more lifelike colors than lower - resolution printers. But resolution doesn't tell the whole tale; some printers are just better at photos while others are better at texts. 　　Speed: After resolution, the most important factor for many buyers is speed. More money buys a faster printer, which is important if you frequently print long texts. 　　Duty cycle: This is the number of pages per month a printer can produce without selfdestroying. It differs from a few hundred pages to thousands. Overwork your printer and it will probably break down, always at the worst possible moment. For ordinary home and school use, duty cycle isn't important, but if you are in a busy office, or you are printing drafts (草稿) of a book, spend a few dollars more for a heavier - duty machine. 　　Ink consumption: Gillette came up with the idea a century ago-sell razors (刮胡刀) cheap and they'll buy your blades (刀片) forever. Printer producers have taken this to heart. In fact, the reason you can buy a decent ink jet for $ 100 is that you'll be buying $30 ink cartridges for life, particularly if you tarn out party invitation, greeting cards, buttons, calendars and other projects. As a rule, low - end printers cost more to operate because their cartridges are smaller and require more frequent replacement. 1．Which of the following can produce the clearest printings of pictures? [　　] A．A faster printer with higher resolution. B．A higher resolution printer. C．A right kind of printer with higher resolution. D．A heavier - duty and higher resolution printer. 2．Supposing Smith is a writer, the best printer for him to buy is ________. [　　] A．a low-end printer B．an expensive printer C．a higher resolution printer D．a heavier - duty printer 3．In the writer's opinion, you can buy a decent ink jet printer at $ 100 because ________. [　　] A．the high price will encourage you to buy $ 30 ink cartridges instead all your life B．the producer is afraid that you will buy $ 30 ink cartridges instead of the ink jet C．the low price will keep you buying $ 30 ink cartridges one after another D．the printer can't work well without the decent ink jet 4．What is the most important in choosing the right ink jet printer? [　　] A．Selecting the cheapest one. B．Buying the most advanced one. C．Meeting your own requirement. D．Printing test pages with a variety of printers.