题目内容：

C

lt's a dog's life for the nation's mutts - who are becoming anxious and aggressive through lack of play， experts fear．

A study of 4，000 dog owners has found a clear link between limited playtime and behaviour problems， such as being nervous when left alone， disobedience and snapping at other animals． And while researchers can't be sure that playing less is directly to blame， they say that games provide vital intellectual stimulation and exercise． The Bristol University study showed that only one in five owners play with their dogs six times a day．  Half play two or three times a day and 10 per cent have just one play session．

Mark Evans， former chief vet for the RSPCA， said that dogs are one of the few animals to play into adulthood．  He told the Sunday Times： 'There is a clear association in the results．  Owners report more potential behaviour problems in dogs that play less．'

Emily Blackwell -- who conducted the research uncovered tonight on Channel 4's Dogs： Their Secret Lives - said dogs often enjoy playing so much that they slow down or change strategy to make the fun last longer． The lecturer in canine（犬科动物） welfare hopes that 10，000 people will eventually fill out the survey． This will enable her to firmly establish whether lack of play is affecting dogs' moods - or if their emotional problems put their owners off spending time with them．  For instance，they may slow down when playing 'chase'， allowing their owner to catch up with them and the game to continue． Favourite games include wrestling， chase and tugging at toys， and perhaps unsurprisingly，'fetch' topped the list． Tennis balls were the favourite toys， followed by soft， squeaky toys， rubber balls and rope toys．

The research comes just days after an animal charity warned that millions of dogs are becoming fat． aggressive and destructive because their owners are clueless about basic animal care．The PDSA said that treats including beer， chips and leftover takeaways are making dogs fat and unwell – and wamed that almost a million are never taken for a walk．

1.If the dogs are not looked after carefully，      ．

A．they may become rebelling and damaging

B．they may get hurt and run away from home

C．they may become less active and dislike playing with the owners

D．they are more likely to fight with other animals

2.What is Emily Blackwell's opinion on dogs' behavior？

A．If the owners spend less time with their dogs， they may become aggressive．

B．Dogs know how to make their playing time last longer．

C．Only a few owners spend enough time playing with their dogs．

D．Some junk food or leftover may cause obesity on dogs．

3.The underlined word "this" in the fourth paragraph probably refers to       ．

A．canine welfare

B．Channel 4's Dogs：Their Secret Lives

C．the survey

D．favourite games

4.What can we learn from the passage？

A．Researchers confirm that playing less is to blame for dogs' bad behaviours．

B．Most of the owners will play with their dogs many times in a day．

C．Chase and tennis balls are the favourites of dogs．

D．It's obvious that dogs' behaviour problems are related with their playing time．