The laptop computer is a small, portable computer that’s light and small enough to hold on your lap. It is smaller than a luggage but larger than a notebook computer. A laptop usually weighs between 8 and 14 pounds, and when folded shut is about the size of a small briefcase. Laptops can be plugged in or run on batteries, although the batteries must be recharged every few hours. Laptop computers use a thin, light weight display screen called a flat-panel display, rather than the cathode ray tube technology of larger personal computers. Laptop displays vary widely in quality. Typically, their display screens show fewer lines than displays on larger computers and can be difficult to read in bright light. Laptops are self-contained units, having their own CPUs, memory, and disk drives. While more expensive than a desktop computer with equivalent computing power, a laptop can be ideal for the on-the-go user who needs a second, portable computer. Laptops aren’t always a suitable replacement for desktop computer, since they can’t be expanded or modified easily should your computing needs change. Also, the display is inferior to standard video graphics array（VGA）displays, although active matrix displays compete well except for size.
膝上型计算机是一种小型便携式计算机，重量轻，机型小，可以放在膝上使用。其形状比行李箱小，但比笔记本电脑大，重量一般在8到14磅左右，折叠起来和小号公文包差不多大小。可以插电源也可以使用电池运行，电池每隔几个小时就必须充电。这类计算机不像较大型的个人电脑那样采用阴极射线管技术，而是采用一种名叫平板显示器的薄型轻质显示屏。膝上型计算机显示器的质量良莠不一。一般而言，其显示屏显示的行数比大型个人计算机少，且在强光下很难看清。膝上型电脑机型虽小然而五脏俱全，拥有自己的中央处理器、内存和光驱。尽管膝上型计算机比功能相当的台式机贵很多，然而对于经常到处奔波而另外需要一台便携式计算机的人来说这种计算机还是很理想的选择。如果用户使用计算机处理信息的需求发生变化，膝上型计算机很难相应地扩大容量或做出其他调整，因此有时用这类计算机来取代台式机也不太合适。而且，虽然膝上型计算机的活性矩阵显示器的屏幕大小可以与影像列阵显示器相媲美，但是总的来说，膝上型计算机的显示器不如标准的影像列阵显示器好。
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