20．
The friendship between humans and dogs possibly began 14000 years ago．Here are four examples of"a dog's life"in the human world today．
Treated like a queen
Tiffy is one of these dogs．Her owner，Nancy Jane Loewy，treats her like a queen．She patiently prepares Tiffy's meals of meat，fish，chicken and different kinds of fresh vegetables．Tiffy also eats yoghurt and biscuits after dinner．Loewy's husband has a very good job and her two sons are away at university，so she has the time and money to treat Titty very well，and she truly enjoys doing it．"I want to give her the healthiest，most wonderful life as long as possible，"she says．
Food sniffer dogs （嗅探犬）
Food sniffer dogs work at international airports in the United States．Their job is to smell and find illegal （不合法的）fruits，vegetables and other foods in bags and mail．These foods sometimes bring insects and diseases which could be dangerous for plants and animals．The dog calmly sits down next to anything that smells suspicious （可疑的）．The dog's human partner then checks for illegal foods．Sniffer dogs are friendly and cute，so they don't scare people as they sniff through the crowds．More importantly these dogs have an astonishing nose for food．They can find food in bags 84% of the time．
Animal carers
Jessic is a whippet （小灵狗）that visits very sick children in hospital．She shows them her love and when they feel down，Jessie makes them happy．Jessie helps patients to stay strong during their time in hospital．
There are many different kinds of animals that help people．We train"service dogs"to help people with physical disabilities．The best known service dogs are guides for the blind．But they can also learn to _______，turn lights on and off，pick up objects from the floor and even pull wheelchairs．
Doggie detectives （侦探犬）
Search-and-rescue （SAR） dogs use their amazing noses to find people．They can smell tiny clues （线索）that people leave wherever they go．These include bacteria （细菌），small pieces of clothing and hairs．They may find missing hikers and search through rubble （碎石）after earthquakes and other disasters．
38．What food does Tiffy eat？D
A．Only yoghurt and biscuits
B．Anything except vegetables
C．Normal dog food from shops
D．Home-cooked meals
39．Which of the following is the best expression to fill in the blank in the passage？B
A．look for missing hikers
B．open and close doors
C．do any tasks for people
D．follow people here and there
40．What kind of dogs is the most helpful when a child is lost？A
A．SAR dogs
B．Whippet dogs
C．Sniffer dogs
D．Queen dogs
41．What's the purpose of the passage？C
A．To introduce different kinds of food sniffer dogs．
B．To tell the readership the importance of protecting animals
C．To show the special relationship between dogs and humans．
D．To share with the readers the pleasure of keeping dogs as pets．
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