B.quite a few
The three-fields system is an agricultural method in which one field out of three is left to lie fallow while the other two fields are being cultivated.
To swim across the English Channel takes at least nine hours. It’s a hard work and it makes you short of breath. To fly over the Channel takes only twenty minutes (as long as you ’ re not held up at the airport)，but it’s an expensive way to travel. You can travel by hovercraft if you don’t mind the noise, and that takes forty minutes. Otherwise you can go by boat, if you forget your sea-sickness ills. All these means of transport have their problems and the weary (不耐烦的）traveler often dreams of being able to drive to France in his own car. “Not possible”，you say. Well, wait a minute. People are once again considering the idea of a Channel tunnel or bridge.
This time，the Greater London Council is looking into the possibility of building a Channel link straight to London. (79) A bridge would cost far more than a tunnel，but you would be able to go by rail or by car on a bridge, whereas a tunnel would provide a rail link only.
Why is this idea being discussed again？ Is Britain becoming more conscious of the need for links with Europe as a result of joining the EEC(欧共体)？ Well, perhaps. The main reason, though，is that a tunnel or bridge would reach the twenty square kilometers of London ’ s disused dockland (船坞地）. A link from London to the continent would stimulate trade and re-vitalize (使 …重新有活力）the port, and would make London a main trading center in Europe. (80) With a link over the Channel, you could buy your fish and chips in England, and be able to eat them in France while they were still warm!
Which of the following statements is TRUE？
A.Swimming across the Channel takes less than four hours.
B.The idea of a Channel tunnel or bridge is a very new one.
C.It is considered to be more difficult to swim across the channel than any other means.
D.A tunnel or bridge would only reach as far as the coast.
The passage suggests that the present day problem with regard to computers is _________.