阅读理解。
People realize that, although animals may not have the same intelligence (智力) as
human beings, they are smart enough to learn certain things.
Dogs are extremely useful as companions for blind people. When a dog has been properly
trained, he will always lead his blind master in the right direction and keep him out of
danger. For example, seeing-eye dogs learn never to cross a busy road when cars are coming,
even if their master ordered them to do so.
Horses are also able to learn many things. Horses that are used for guard or police
duty must learn never to be frightened of noises, traffic, and other disturbances. Racing
horses are able to run much faster than other horses, but they are also quite high strung
(易紧张). Therefore, it is necessary for those people who train them to be very patient
(耐心) and understanding.
The moving pictures and television can use trained animals too. Some animals, such as
monkeys and foxes, are easy to film. All you have to do is make a trail in front of the
camera by dragging something that smells good to the animals over the ground. Big animals,
such as lions and tigers, can be photographed as they bound happily back to their families
and dinner. If a movie actor is nearby, the well-trained animal will pay no attention to
him. However, the audience may imagine that the actor escaped a terrible death by the skin
of his teeth.
1. Dogs who help blind people must learn _____. [ ]
A. to obey all orders
B. to obey only safe orders
C. never to cross roads
D. to cross road when ordered to do so
2. Race horses are hard to train because they are _____. [ ]
A. faster than other horses
B. smaller than other horses
C. clever than other horse
D. more nervous than other horses
3. What does "make a trail" mean here in the last paragraph? [ ]
A. place something to attract the animal
B. give the animal a certain task
C. order the animal to do things
D. follow the animal to hunt
4. Lions can be photographed easily when _____. [ ]
A. they are following a trial of something that smells good to them
B. they are returning to their families
C. they have been trained to work with other animals
D. they do not know a movie-actor is nearby
2Fe+CO2； （3）复分解反应．