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问题 选择题

如右图所示，在光滑的水平面上，一质量为m，半径为r，电阻为R的均匀金属环，以初速度v0向一磁感应强度为B的有界匀强磁场滑去(磁场宽度d>2r)．圆环的一半进入磁场历时t秒，这时圆环上产生的焦耳热为Q，则t秒末圆环中感应电流的瞬时功率为(　　)

A．

B．

C．

D．

答案

答案：B

题目分析：设t秒末圆环的速度为v． 根据能量守恒得：  ①

此时圆环中感应电动势为  ②

圆环中感应电流的瞬时功率为 ③

联立①②③得

故选B

点评：本题电磁感应中能量问题，根据能量守恒求出速度是关键

单项选择题

甲出差前将家中的一台彩电交由邻居乙保管。在甲出差期间，乙将彩电卖给丙，丙以为彩电为乙所有。便以合理价款购得。对此

A．甲不得向丙请求返还彩电

B．甲可要求丙返还彩电

C．甲可要求乙与丙共同承担赔偿责任

D．甲可要求丙赔偿损失
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问答题

请根据信用证和补充资料缮制托运单。


(1)信用证


SEQUENCE OF TOTAL *27：1/1
FORM 0F DOC CREDIT *40A：IRREVOCABLE
DOC．CREDIT NUMBER *20：5715255123
DATE OF ISSUE 31C：090312
DATE AND PLACE OF EXPIRY *31 D：090615 IN CHINA
APPLICANT*50：MAMUT ENTERPRISESAV
TARRAGONA75-4
BARCELONA，SPAIN
BENEFICIARY *59：XIAMEN HONGYUN CORPORATION
223 GANXIANG ROAD
XIAMEN．CHINA
AMOUNT *32B：CURRENCY USD AMOUNT 25560.00
AVAILABLE WITH/BY *41D：ANYBANK IN CHINA
BY NEGOTIATION
PARTIAL SHIPMENTS 43P：ALLOWED
TRANSSHIPMENT 43T：NOT ALLOWED
LOADING 0N BOARD 44A：XIAMEN
FOR TRANSPORTATION TO 44B：BARCELONA(SPAIN)
LATEST DATE OF SHIPMENT 44C：090601
DESCRIPT OF GOODS 45A：HAND TOOLS
AS PER PROFORMA INVOICE NO．56941
CFR BARCELONA
DOCUMENTS REQUIRED 46A：
SIGNED COMMERCIAL INVOICE．3 FOLD．
PACKING LIST．3 FOLD．
FULL SET CLEAN ON BOARD OCEAN BILL OF LADING ISSUED TO THE ORDER
OF SHIPPER．MARKED FREIGHT PREPAID AND NOTIFY APPLICANT．
CHARGES 71B：ALL BANKING CHARGES 0UTSIDE SPAIN
ARE FOR ACCOUNT 0F BENEFICIARY．
PERIOD FOR PRESENTATION 48：DOCUMENTS MUST BE PRESENTED
WITHIN 15 DAYS AFTER THE DATE
OF SHIPMENT BUT WITHIN THE VA．
LIDITY 0F THE CREDIT．

(2)补充资料


INVOICE NO．JSCO96814
PACKING G．W/kgs N．W/kgs MEAS/(m3)
HAND TOLLS
ART01: Packed in 1 wooden case of 1500 pcs each 1380/case 1730/case 0.4/case
ART02：Packed in 1 wooden case of 1000 pcs each 1030/case 1020/case 0.3/case
Packed in ONE 20’CONTAINER(集装箱号：TEXU2263978)
唛头：HAND TOOLS
BARCELONA
C/N0．1-5
金发编号：JF0387458
人民币账号：RMB06128614
生产厂家：厦门工具厂

(3)托运单
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