设Z是整数集合,+是一般加法,则下列函数中哪一个不是群的自同态( )
A. f(x)=2x
B. f(x)=1000x
C. f(x)=|x|
D. f(x)=0
设为加群,0是其单位元,在R上定义运算∘,对任意a,b∊R,a∘b=0,那么 ( )
A. 不能构成环
B. 不一定能构成环
C. 能构成环
D. 能构成域
设代数系统中运算⨁,⨂定义如下:对任意整数a,b∊Z,a⨁b=a+b-1, a⨂b=a+b-ab (这里的加和乘都是普通的加法和乘法运算)那么是( )
A. 能构成环
B. 能构成含幺环
C. 能构成含幺交换环
D. 能构成域
网络查询典型船公司航线的运价本等信息,学习查询各家船公司主要航线、船期表、运价本等信息,学习比较不同船公司统一航线的运价和航线服务,并根据模拟的货代公司的数据制作运价表。第一步:向船公司发出询价英文信函例:市场部小李向OOCL船公司发出询盘Re: Ocean Freight enquiry on Mar.—fm Victory Freight Forwarder Co.Dear Jackee,This is Lee fm Market dept. of Victory Freight Forwarder Co. and Jackson introduce writer to direct contact with you for o/f quotation.Hope can get your support and help in future.Could you kindly provide your freight list on Mar for us ref so that we can timely update our record and try to canvass more cargo on your liner service?Your prompt reply and comment will be highly appreciated.If any query please feel free to ctc with writer.Tks&b.rgdsLeeMarket DepartmentVictory Freight Forwarder Co.Tel: +86-771-5556888 / Fax:+86-771-5556999Mobile: +86-13978866999E-Mail: lee@victory-forwarder.com第二步:根据船公司给出的运价成本区分出不同的港口所属航线例如:OOCL船公司根据小李的邮件回复如下:Re: Ocean Freight enquiry on Mar.—fm Victory Freight Forwarder Co.Dear Lee,Nice to meet you!Please refer our update rate quotation ex Shekou,Shenzhen in Mar and should you have any enquiry don’t hesitate to let me know.Thanks.* Above rate incl the baf and other surcharge,subject to thc and doc fee USD20/Bill* Thc quantum in USD will be increased to USD55/84/84 wef 10/Aug/2008If any potential cargo could raise application to us case by case.Best Regards.Jackee第三步:计算防城港起步运价,制作运价表防城港至蛇口的驳船运费为USD350/20’,对照世界航线港口表后列出各航线对应的港口,并按照运费计算方法:防城港至蛇口驳船费+蛇口海运费+THC算出运价后填制防城港起步运价表: