阅读理解。 Dogs have long been used to find

题目：

阅读理解。

     Dogs have long been used to find explosives and drugs. Now, a new study shows that man's best friend

can also help to find lung and breast cancer, researchers report in integrative Cancer Therapies. The findings

show that trained ordinary household dogs can detect early-stage lung and breast cancers by smelling the

breath samples of patients.

     Researchers have found that cancer cells send out molecules different from those of healthy ones, and that

might be sensed by smell by the highly sensitive dog's nose.

     For the study, five dogs were trained by a professional instructor to respond differently to breath samples

of healthy and cancer patients. "The dogs learned to sit or lie down in front of cancer patient samples and to

ignore control samples through the method of food reward," McCulloch explained.

     After a period of training,researchers tested the animals' ability to distinguish cancer patients from controls.

The animals were given breath samples from 55 patients with lung cancer, 31 with breast cancer and 83 healthy

controls who were not included in the original training period.

     McCulloch's group found that the dogs were able to correctly distinguish the breath samples of cancer

patients from those of the control subjects in about 90 percent of the cases. The dogs were also able to

detecting early-stage lung and breast cancers.

     "These results show that there is hope for early detection," McCulloch said. The re-searches are planning to

conduct further studies on the breath composition of cancer patients to possibly design an electronic device that

can do the dogs' job. "A dog's nose is so powerful it can detect odors (气味) 10 000 to 100 000 times better

than a human nose can. I hope people will be interested in doing this research," McCulloch added, "It shows

that there is definitely something out there."

1. McCulloch and his group used _____ in their research.

A. 10 dogs and 55 people

B. 5 dogs and 86 people

C. 10 dogs and 83 people

D. 5 dogs and 169 people

2. The underlined word "distinguish" means _____.

A. to make somebody feel better

B. to recognize differences of

C. to remember somebody forever

D. to discomfort somebody

3. We can infer from the passage that _____.

A. dogs can smell signs of other cancers except the above two kinds

B. the final goal of the researchers is to design an electronic dog to detect cancer

C. dogs can detect odors 10 000 to 100 000 times better than humans can

D. dogs will soon be widely used to smell signs of cancers in hospitals

4. Which of the following would be the best title?

A. Special Noses of Dogs

B. Dogs and Cancer

C. Dogs Smell Signs of Cancer

D. McCulloch's New Discovery