22. The writer says that 8t a circus we can see animals doing cIever tricks.
23. The trainer usually gives the animal a piece of candy or fruit after it has done the trick.
24. The reward in the passage means "attention paid to a good behavior".
25. Many animals may be trained to do simple jobs if they know who their trainers are.
26. Geese can be used to guard a house.
27. When the pigeon sees a ball which looks different from the others , it makes a noise.
28. Trainer usually spends 40 days or so training a pigeon to inspect sm811 steel balls.
29. An ape is a large monkey.
30. Scientists believe apes may drive buses one day.
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