题目内容：

Dogs are man’s best friends---they are very good for children’s health. Researchers found that family pets helped to protect babies against breathing problems and infections (感染).

A team from Kuopio University Hospital in Finland studied 397 babies born at their hospital between September 2012 and May 2015 for their first year. They found that babies who lived with a dog or a cat spent fewer weeks with ear infections, coughs or runny noses. They were also less likely to need antibiotics (抗生素) than babies in homes without a pet.

Study author, Dr. Eija Bergroth, said dogs brought dirt and bacteria (细菌) into the home, which helped children’s immune system (免疫系统) to be strong. This improved their defenses against bacteria.

As part of the study, parents filled out weekly diaries starting when the children were nine weeks old, recording information on babies’ health as well as their contact with cats and dogs. They recorded if they had fever, ear infections, coughs or running noses. They also put down whether they needed antibiotics.

Based on those diaries, the researchers found that about a third of the children spent most of their first year with a pet dog and 24 percent in a home with a cat. And children with no dog contact at home were healthy for 65 percent of the time, compared to between 72 and 76 percent for those who did have a pet.

The researchers also found that contact with dogs, more than cats, was tied to fewer weeks of sickness for babies.

However, the researchers said they couldn’t rule out the possibility that people who own dogs are less likely to get sick for another reason, not due to any protection offered by pets.

1.The researchers studied each child’s life ____.

A. for a year

B. for three years

C. for four years

D. all through childhood

2.How are dogs able to benefit children?

A. By fighting bacteria.

B. By stopping them from going out.

C. By strengthening their immune system.

D. By producing the antibiotics they need.

3.What do the underlined words, “rule out”, in the last paragraph probably mean?

A. Determine.    B. Separate.

C. Control.    D. Ignore.

4.We can learn from the text that ___.

A. dogs are very friendly towards people.

B. dogs are better for babies’ health than cats.

C. dogs have the most benefits for man.

D. dogs are free from antibiotics.