relieve symptoms of depression and encourages people to be more positive.

5.__5__ Dogs can be effective home security system. Just knowing that you've got a dog who can use its keen sense of hearing to detect anyone walking around can help increase your sense of security, which is good for both your mental and physical health.

A．You'll feel safer.

B．Dogs can replace security system.

C．You can never imagine your dog can be of so much benefit. D．Therefore, dog owners are more likely to have a healthy heart. E．The benefits of dog ownership extend to your mental health as well. F．People are more likely to stop and talk with you when you're walking a dog. G．Taking your dog for a 30 minute walk every day can greatly improve your health. 文章大意：养条宠物狗好处多多。

1．G 根据上句“...your dog...waiting to go for a walk”可知，带狗外出散步可以连接上文。 2．F 与上文“a date”以及该段主题句“Your social life may improve”照应的是F项，在你遛狗时，人们很可能会停下来和你交谈。

3．D 与主题句“Your heart will be healthier”相照应，以及空前的“...lowers a person's heart rate”可知，选D项，狗的主人的心脏会更加健康。

4．E 由该段主题句“You're less likely to feel depressed ”可知，E项心理健康符合语境。 5．A 该空为该段的主题句。由该段的“security”可知，A项“你会更加安全”符合语境。