A dog's mind is only equal to that of a two-year-old baby．（36） ______ So，they are probably the first to notice any change in the behavior of their masters．Let's do some deep-digging to understand the amazing ability of a dog．
They sense your feelings．Isn't it strange（37） ______ This is true．A study published in the Animal Cognition（认知）journal says that dogs are known to come to people who appear sad or depressed．It doesn't matter if the person is their owner or a stranger．They have an ability to sense sadness and are attracted to troubled souls．
（38） ______ Dogs can easily tell when you're playing with favorites，and if you reward or play more with other pets，your dog might notice it and feel uncomfortable．As they can't say how they feel，they will scratch，yawn or lick their mouths．
They smell fear．Let's say you are faced with your worst fear．Would you get scared and run away or just face it？Before choosing how to deal with it，you should remember one thing．（39） ______ Research shows that dogs often sense their master's response in dangerous situations．If you fear something and choose to back away，chances are that your pet is going to do the same thing．
They're watching you．We are all raised as responsible individuals who are taught to respect elders，obey the law and help out people in need from time to time．（40） ______ But if you have a dog at home，it is time to be serious about them．Dogs like generous people．So just be careful around your pet； it may judge you on how you behave with others．

A．They sense health problems．
B．They understand when ignored．
C．They know when no one's looking at them．
D．You would be setting an example to your pet．
E．Every time you feel sad，your dog just knows it．
F．But dogs are able to sense everything around them．
G．However，not all of us take these three things seriously．

(1) A. A

B. B

C. C

D. D

E. E

(2) A. A

B. B

C. C

D. D

E. E

(3) A. A

B. B

C. C

D. D

E. E

(4) A. A

B. B

C. C

D. D

E. E

(5) A. A

B. B

C. C

D. D

E. E