题目内容：

阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

Dogs were first raised at home at least 150 centuries ago. Since then, the dog 1. (be) humans’ best friend. Now, they have another job — to help doctors to diagnose (诊断) cancer.

After a long-standing research of smell, a Finnish professor has said that certain 2. (type) of cancer are able to be discovered by their smell, 3.(make) it possible to train cancer-sniffing dogs to help diagnose the disease.

A professor, JoukoVepsalainen from the University of Eastern Finland in Kuopio, has focused on nitrogen compounds (氮化合物). The compounds increase 4. (great) when cancer cells grow in an uncontrollable way, allowing them 5.(find) out, the Finnish newspaper Karjalainen reported. That’s where the dog, man’s best friend, may step in with their sharp sense of smell.

According 6. the news agency, researchers in Finland have tried to train dogs to do the job, but 7. will take a dog months, even years, to tell the 8. (different) between sick and healthy people. “Anyone 9. knows how difficult early cancer detection (察觉) is understands 10. a good opportunity this is,” associate professor Anna Hielm-Bjorkman of the University of Helsinki told the Finnish media.