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

　　第三篇答案BCDAA