题目

两根通电的长直导线平行放置，电流分别为I1和I2，电流的方向如图所示，在与导线垂直的平面上有a、b、c、d四点，其中a、b在导线横截面连线的延长线上，c、d在导线横截面连线的垂直平分线上．则导线中的电流在这四点产生的磁场的磁感应强度可能为零的是( )A．a点B．b点                                     图10C．c点                  D．d点  The loveliest house that I have ever lived in was one that my grandparents owned. This house was called Crosslands. I lived there when I was a child. I had some very happy times at Crosslands. It seemed so big to me as a child. It had a big beautiful living room with a piano in it and a large hall. There was a mysterious drawing room which we only used on Sundays or on special occasions.I used to be amazed by this room because it had the best furniture in it, but it was covered up with sheets(床单). It was as if all the furniture was wearing clothes and it seemed ridiculous to me that we couldn't enjoy this lovely furniture all week long.The kitchen had lovely red floor, which was always polished, and one big heater to heat the whole room so it was always warm. There was also kind of clotheshorse(晒衣架) above it that we used to hang all our stuff on, and it was just lovely. It was a very warm room and my grandmother used to make ice cream that we'd eat there.I spent a lot of time in the vegetable garden picking peas and eating them. My grandmother used to get really angry with me because I would pick all the vegetables and fruit for dinner, but eat half of it before she could start cooking. The homegrown food tasted so fresh and delicious. I went back to Crosslands a few years ago but it turned out to be a big mistake. They've modernized the house and gotten rid of those lovely old fireplaces. They've also knocked wall down so the drawing room and living room have become one big, modern room. I think the house has become smaller and my memory of this lovely, large, warm, comfortable house was completely different.It taught me a valuable lesson: ________________________________________.1.Is Crosslands a house which the writer's grandparents once owned?____________________________________________________________________________________________2.Where did the writer's family hang all their stuff?____________________________________________________________________________________________3.Why did the writer's grandma get angry with him?____________________________________________________________________________________________4.How did the homegrown food taste?____________________________________________________________________________________________5.Why did the writer think going back to Crosslands was a big mistake?____________________________________________________________________________________________6.Complete the last sentence.____________________________________________________________________________________________