题目内容
计算机通过电话网拨号方式上网时，异步传输的字符同步，下列选项(18)的说法是正确的；采用数据位为8位的异步起止方式传输数据时，其效率最高为(19)，高级数据链路控制规程(HDLC)是(20)提出的标准；HDLC帧同步标志是(21)；HDLC协议为保证帧同步标志路上传输时的惟一性，对数据进行的处理是(22)字节。
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True, my heat pump runs on electricity-an expensive commodity where I live. But most of its energy comes from the earth: a propylene-glycol solution circulates through 1,200 feet of two-inch-diameter plastic pipe buried three feet deep in a field next to my house. As it travels, the solution absorbs heat from the surrounding soil, even when soil temperature drops below freezing.
My ground-source heat pump also offers important benefits that have nothing to do with economics.
-Minimal fire hazard-no chimney, firebox, or heating elements-only pumps, fans, and a compressor.
-Cleanliness-no combustion products, thus no chance of my heating system polluting the indoor air, leaving scummy deposits on walls and furniture.
-Reliability-solid-state electronic controls and sealed beatings almost eliminate breakdowns.
-No maintenance-no wood to cut, ashes to haul, or chimney to clean.
-Convenience-The system runs automatically, even switching from heating to air conditioning as needed. I can simply lock the door and go away for a day, week, or month.
Not only did I expect to start saving on energy costs immediately, but I also expected those savings to grow over the years as oil process continued to soar. Since I was wrong about oil prices, the big dollar savings I' d hoped for haven' t materialized. Nevertheless, I am satisfied, all things considered.
The passage suggests that the author' s heat-pump system absorbs heat from ______.
听力原文： The chief judge at the war crimes trial of the former Yugoslavia President Slobodan Milosevic has called for a radical review of proceedings after the trial was adjourned because of the defendant's ill health. In a short but dramatic hearing at The Hague, the judge read a medical report, saying Mr. Milosevic was suffering from extremely high blood pressure and needed a rest. Mr. Milosevic, who's insisted on conducting his own case, had been due to begin setting out his defense. The judges will announce on Tuesday how they intend to proceed.
What can be learnt about the trial？
【C18】
公司分配当年税后利润时,应当提取利润的()列入法定公积金。
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