In a society where lung and breast cancers are leading causes of cancer death worldwide, early detection of the disease is highly desirable. In a new scientific study, researchers present astonishing new evidence that man's best friend, the dog, may have the ability to contribute to early cancer detection.

Researchers show scientific evidence that a dog’s extraordinary smelling ability can distinguish people with both early and late stage lung and breast cancers from healthy people. Researchers first discovered this in the case report of a dog warning its owner to the presence of a melanoma (恶性黑素瘤) by constantly sniffing the skin lesion (损伤). Later studies published in major medical magazines proved the ability of trained dogs to detect both melanomas and bladder cancers. The new study is the first to test whether dogs can detect cancers only by sniffing the breath of cancer patients.

In this study, five household dogs were trained within a short 3-week period to detect lung or breast cancer by sniffing the breath of cancer patients. The experiment consisted of 86 cancer patients (55 with lung cancer and 31 with breast cancer) and 83 healthy people. All cancer patients had recently been diagnosed with cancer and had not yet undergone any chemotherapy treatment (化疗). The dogs were presented with breath samples from the cancer patients and the healthy ones, captured in a special tube. Dogs were trained to give a positive identification of a cancer patient by sitting or lying down directly in front of a test station containing a cancer patient sample, while ignoring healthy samples.

The results of the study showed that dogs can detect breast and lung cancer between 88% and 97%. Moreover, the study also proved that the trained dogs could even detect the early stages of lung cancer, as well as early breast cancer. The researchers concluded that breath analysis might become a potential of cancer diagnosis.

56. What's the best title of the passage?

  A. Can dogs smell cancer?                      B. Dogs and treatment

 C. A new research on breast cancer        D. An interesting experiment on lung cancer

57. In this scientific study, five household dogs, _____lung cancer patients and        healthy people are involved.

  A. 86; 88            B. 31; 97          C. 55; 83           D. 86; 83

58. The last sentence of the passage means       .

  A. doctors won’t be worried about detecting cancers any more

  B. dogs will be the only way to detect cancers

  C. breath analysis can be used in diagnosing cancers in the future

  D. dogs can use its smell to identify people

59. The research found that dogs could help detect cancers by_______.

   A. being captured in a special tube        

B. sniffing the skin lesion

   C. sniffing the breath of the cancer patients 

D. sitting or lying down before a cancer patient