以太网的MAC协议提供的是
A.无连接不可靠服务
B.无连接可靠服务
C.有连接不可靠服务
D.有连接可靠服务
参考答案:A
解析:以太网的MAC提供的是无连接的不可靠的服务。
Flying over a desert area in an airplane, two scientists looked down with trained eyes at trees and bushes. After an hour’s flight one of the scientists wrote in his book, "Look here for probable metal. " Scientists in another airplane, flying over a mountain area, sent a message to other scientists on the ground, "Gold possible. " Walking across hilly ground, four scientists reported. "This ground should be searched for metal." From an airplane over a hilly wasteland a scientist sent back by radio one word: "Uranium." None of the scientists had X-ray eyes: they had on magic powers of looking down below the earth’s surface, They were merely putting to use one of the newest methods of locating minerals in the ground, using trees and plants as signs that certain minerals may lie beneath the ground on which the trees and plants are growing. This newest method of searching for minerals is based on the fact that minerals deep in the earth may affect the kind of bushes and trees that grow on the surface. At Weston Bar Greek, a brook six thousand feet high in the mountains of British Columbia, Canada, a mineral search group gathered bags of tree seeds. Boxes were filled with small branches from the trees. Roots were dug and put into boxes. Each bag and box was carefully marked. In a scientific laboratory the parts of the forest trees were burned to ashes and tested. Each small part was examined to learn whether there were minerals in it. Study of the roots, branches, and seeds showed no silver. But there were small amounts of gold in the roots and a little less gold in the branches and seeds. The seeds growing nearest to the tree trunk had more gold than those growing on the ends of the branches.
Which is the best title suggested below
A.Scientists Searching for Metals with Special Power.B.New Methods of Searching for Minerals.C.Gold Could Be Found by Trees and Plants.D.A New Method of Searching for Minerals—Using Trees and Plants.
北方股份有限公司(下称北方公司)为增值税一般纳税人,增值税税率为17%(凡资料中涉及的其他企业,需交纳增值税的,皆为17%的税率)。北方公司发生如下经济业务: (1)2008年1月1日,北方公司应收南方公司货款余额为1300万元,已计提坏账准备300万元。2008年2月10日,北方公司与南方公司达成协议,南方公司用一批原材料抵偿上述全部账款。3月1日,南方公司将材料运抵北方公司, 2008年3月2日双方解除债权债务关系。该批原材料的公允价值和计税价格均为1000万元,发票上注明的增值税额为170万元。 (2)北方公司收到的上述材料用于生产A产品。 2008年6月30日,假设利用该批原材料所生产的A产品售价总额由1450万元下降到1320万元,但生产成本仍为1400万元,将上述材料加工成产品尚需投入400万元,估计销售费用及相关税金为10万元。若把该批材料对外销售,该批材料的市场价为900万元,估计销售材料的销售费用和税金为6万元。 (3)2008年8月20日,因北方公司欠东方公司的原材料款600万元不能如期归还,遂与东方公司达成债务重组协议: ①用银行存款归还欠款100万元,②用所持某上市公司股票100万股归还欠款,股票在债务重组日的收盘价为400万元,该股票作为交易性金融资产反映在账中,其账面余额为380万元(成本为350万元,公允价值变动为30万元)。假设在债务重组中没有发生除增值税以外的其他税费。当日办完有关产权转移手续并解除债权债务关系。 (4)2008年12月31日,因上述债务重组业务从南方公司取得的材料已发出60%用于产品生产,结存40%,已计提的存货跌价准备尚未结转。因A产品停止生产,结存的上述材料不再用于生产产品。若把该批材料对外销售,该批材料的市场价为410万元,估计销售材料的销售费用和税金为3万元。 (5)2009年3月20日,北方公司将上述剩余的材料与南方公司的一台设备进行资产置换,资产置换日,原材料的公允价值为410万元,增值税为69.7万元,南方公司设备的公允价值为479.7万元。 要求: (1)确定北方公司与南方公司的债务重组日,并编制北方公司债务重组日的会计分录。 (2)判断2008年6月30日该批原材料是否发生减值。若发生减值,编制原材料计提减值准备的会计分录。 (3)编制北方公司与东方公司债务重组的会计分录。 (4)编制北方公司2008年12月31日计提或转回存货跌价准备的会计分录。 (5)编制2009年3月20日北方公司资产置换的会计分录。(答案中金额单位用万元表示)