控制单元(CU)控制运算单元和寄存器组正确地实现要求的操作。以下不属于控制单元(CU)组成部件的是______。
A．程序计数器
B．指令寄存器
C．时序产生器
D．多路转换器
参考答案：D
解析： 控制单元(CU)控制运算单元(ALU等)和寄存器组正确地实现要求的操作。例如，对指令进行译码的功能是由控制单元实现的。
控制单元(CU)通常由程序计数器(PC)、指令寄存器(IR)、指令译码器、状态/条件寄存器(PSW)、时序电路、微操作信号发生器等组成。而多路转换器是运算器的组成部件。
Culture shock isn’t a clinical term or medical condition. It’s simply a common way to describe the confusing and nervous feelings a person have after leaving a familiar culture to live in a new and different culture. It’s natural to have difficulty adjusting to a new culture. People from other cultures may have grown up with values and beliefs that differ from yours. Because of these differences，the things they talk about，the ways they express themselves and the importance of various ideas may be very different from what you are used to. But the good news is that culture shock is temporary. What causes culture shock? To understand culture shock，it helps to understand what culture is. You may know that genes determine a big part of how you look and act. What you might not know is that your environment has a big effect on your appearance and behavior as well. Your environment isn’t just the air you breathe and the food you eat，though；a big part of your environment is culture. Culture is made up of the common things that members of a community learn from family，friends，media，literature，and even strangers. These are the things that influence how you look，act，and communicate. Often，you don’t even know you are learning these things because they become secondnature to you－for instance，the way you shake hands with someone，the kind of things you find funny，or how you view religions. The differences between cultures can make it very difficult to adjust to the new surroundings. When you go to a new place，such as a new country or even a new city，you often enter a culture that is different from the one you left. Sometimes your culture and the new culture are similar. Sometimes，they can be very different. What might be perfectly normal in one culture－for example，spending hours eating a meal with your family－might be unusual in a culture that values a more fastpaced lifestyle.
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