1.What effect does exceeding positive ionization have on some people?

　　A.They think they are insane.

　　B.They feel rather bad-tempered and short-fussed.

　　C.They become violently sick.

　　D.They are too tired to do anything.

　　2.In accordance with the passage, static electricity can be caused by___.

　　A.using home-made electrical goods.

　　B.wearing clothes made of natural materials.

　　C.walking on artificial floor coverings.

　　D.copying TV programs on a computer.

　　3.A high negative ion count is likely to be found___.

　　A.near a pound with a water pump.

　　B.close to a slow-flowing river.

　　C.high in some barren mountains.

　　D.by a rotating water sprinkler.

　　4.What kind of machine can generate negative ions indoors?

　　A.Ionisers.

　　B.Air-conditioners.

　　C.Exhaust-fans

　　D.Vacuum pumps.

　　5.Some scientists believe that___.

　　A.watching animals to anticipate earthquakes is more effective than depending on seismography.

　　B.the unusual behavior of animals cannot be trusted.

　　C.neither watching nor using seismographs is reliable.

　　D.earthquake cannot affect any animals