20．
There are about 80.000.000mines under the ground in more than 60countries．It is difficult and dangerous to clear these mines．About 50people including many children were killed or hurt each day．In 2003，APOPO，a Duch research company that trains the animals，came up with the idea of using rats to search for the mines．
The animal trainers found that a kind of rats from Africa were clever and had a sharp sense of smell．The rats were about 75cm long and weighted about 1.35kg．light enough to run across a minefield without setting off the mines．
In January 2004，the APOPO started this project．First，the trainers let the 4-week-old baby rats get familier with humans．A few weeks later，the rats were no longer afraid of people and the things around them．Then they were trained to connect a click sound with food．After the rats had learned that，the trainers then taught them to tell the different between the smell of mines and other smells．When the rats could do it，the click was sounded and they were given a bit of bananas．The method was called clicker training．"The training isn't easy．"said the trainer Adulish Mebomvu．"You have to be patient．Sometimes I get angry，but then again．I tell myself these are animals．"
After nine months'training，the rats were taken to 4minefield．They ran across the minefield，stopped，sat and searched the ground to tell the deminers that they smelt out a mine．Then the mine was cleared．It had taken two deminers a day to clear a 200m
2 minefield．But with the help of two rats they could finish it in two hours．
The rats and the deminers saved thousands of lives．"The rats did this job much better than we expected．So far they have helpde to make almost 2.000.000m
2 of land safe．They are heroes．"said Bart Woetjcds．the head of the APOPO．
29．The APOPO trained the rats to search forC
A．children B．animals C．minea D．bananas
30．While training the rats，the trainers have to beA
A．patient B．clever C．brave D．serious
31．How long did the training last？D
A．Two hours B．One day C．Four weeks D．Nine month
32．Which of the following is NOT TRUE acorrding to the passage？A
A．Each day about 200people were killed or hurt by minea
B．The APOPO started to train the rats is January 2004．
C．The trainers gave the rats food after they smelt out a mine．
D．The rats and the deminres saved thousands of livers．
