额定电压为6V的用电器与4Ω的电阻串联后，接入电源，它正常工作，此时电路电流为0 发布时间：2017-04-21 12:04 │ 来源：www.tikuol.com 题型：填空题 问题： 额定电压为6V的用电器与4Ω的电阻串联后，接入电源，它正常工作，此时电路电流为0.5A，则用电器的电阻为__________Ω，电源电压为_________V。
题型：填空题 阅读理解。 David's got a text message from his friend Sam. Can you understand it? 7,15 20,15 20,8,5 16,1,18,11 This message was in code (密码, 代码). How many letters are there in the English alphabet? Twenty-six. So can you read it now?A B C D E F G H I J K LMNOPQRSTU...123456789101112131415161718192021... David decided to use a different code in his answer to Sam. This time, he was putting A instead of B,B instead of C, and so on. His message to Sam shown on the right was very short. Can you understand?ABCDEFGHIJKLMNOPQRSTUVWXYZBCDEFGHIJKLMNOPQRSTUVWXYZA Sam guessed David's code, and he replied: ZESDQ, RBGNNK. When David's little sister saw the message,she felt puzzled. She couldn't read it at all. But David was very happy that his sister couldn't read his message! Lots of people use codes to send secret messages. In a war, secrets are very important so soldiers often send each other messages in code. Nowadays, we can use computers to make and break difficult codes. Evenbefore computers, people invented other machines to do this. Here's a famous machine that Germans used in the Second World War (1941-1945). It's called the Enigma Machine. The machines were very big, heavy and expensive. Every day they changed the codes automatically, and this made it almost impossible for anyone to break the codes. The person sending a message had onemachine, and the person receiving the message had another. 1．Sam asked David to go to the ______.[ ]A．park B．houseC．museum D．zoo 2．Sam told David to meet him ______.[ ]A．before breakfastB．after school C．after dinner D．before school 3．Codes are used to keep something ______. [ ]A．newB．old C．secretD．known 4．People will never know the meaning if they can't ______ the code. [ ]A．break B．make C．change D．write 5．The best title of this passage is .[ ]A．English LettersB．Codes C．Messages D．Machines 查看答案
题型：填空题 计算下列各题．（能用简便算法的用简便算法）6.73×4.8+5.2×6.73．1.6×[（12-7.2）÷（0.84÷2.1）]．81÷[（3.25+6.75）×0.09]．0.45×78.2+20.8×0.45+0.45． 查看答案
题型：填空题 “一国两制”构想的提出和实践（）。A.坚定不移地奉行独立自主的和平外交政策B.同世界各国建立和发展友好关系C.反对霸权主义和强权政治，维护世界和平D.推动社会发展，促进人类进步E.贯彻“一国两制，和平统一”的方针 查看答案