加在某导体两端的电压为6伏时，通过导体的电流为0．5安，则该导体的电阻为____ 欧；若加在导体两端的电压变为12伏时，导体中的电流为____ 安，导体的电阻为 ____欧。

如图所示，电阻忽略不计的光滑平行导轨MN、PQ倾斜放置，倾角为θ，间距为L，以垂直于导轨的虚线a，b，c为界，a、b间和c与导轨底端间均有垂直于导轨平面向上的均强磁场，磁感应强度均为B，导体棒L₁，L₂放置在导轨上并与导轨垂直，两棒长均为L，电阻均为R，质量均为m，两棒间用长为d的绝缘轻杆相连，虚线a和b、b和c间的距离也均为d，且虚线c和导轨底端间距离足够长，开始时导体棒L₂位于虚线a和b的中间位置，将两棒由静止释放，两棒运动过程中始终与导轨接触并与导轨垂直，棒L₂刚要到达虚线c时加速度恰好为零，重力加速度为g，求：

    孔乙己是站着喝酒而穿长衫的惟一的人。①他身材很高大；②青白脸色，③皱纹间时常夹些伤痕；④一部乱蓬蓬的花白的胡子。穿的虽然是长衫，可是又脏又破，似乎十多年没有补，也没有洗。他对人说话，总是满口之乎者也，教人半懂不懂的。因为他姓孔，别人便从描红纸上的“上大人孔乙己”这半懂不懂的话里，替他取下一个绰号，叫作孔乙己。孔乙己一到店，所有喝酒的人便都看着他笑，有的叫道，“孔乙己，你脸上又添上新伤疤了！”他不回答，对柜里说，“温两碗酒，要一碟茴香豆。”便排出九文大钱。他们又故意的高声嚷道，“你一定又偷了人家的东西了！”孔乙己睁大眼睛说，“你怎么这样凭空污人清白……”“什么清白？我前天亲眼见你偷了何家的书，吊着打。”孔乙己便涨红了脸，额上的青筋条条绽出，争辩道，“窃书不能算偷……窃书！……读书人的事，能算偷么？”接连便是难懂的话，什么“君子固穷”，什么“者乎”之类，引得众人都哄笑起来：店内外充满了快活的空气。

    Singapore's public transport system is one of the best in the world, so you should have no problem finding your way around like a local. There are three main forms of public transport that you would find in any other major city—trains, buses and taxis.

    TRAINS

    Trains run from 6:00 am to midnight. Single trip tickets start at 80 cents. If you buy an EZ-Link cars for $15, you can ride the trains and buses as you like.

    If you need more information, just call Transit Link on 1800 525 7333.

    BUSES

    There are several bus services in Singapore and fares start at 80 cents. Be sure always ask the driver the cost of your ticket as he can not give change.

    If you need help, just call Transit Link on 1800 525 7333.

    TAXIS

    There are three main taxi companies—City Cab (6552 2222), Comfort (6552 1111) and Tibs (6552 8888). Booking can also be easily by calling the numbers listed above.

    RENTAL CARS

    Driving in Singapore is a pleasure and if you liked to travel at your own pace, renting a car is a good choice. Renting takes away the hassle of getting to places around Singapore. Just sit back and enjoy the city. It also means you'll get to see a lot more that a train or a bus won't let you see.

    For car rental, call Avis on + 65 6737 1668.