根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。
1 It might understand more than you think． 
A dog named Rico recognizes the names of about 200 objects，say researchers in Germany．  2 Its word-1earning skills are as good as those of a parrot or chimpanzee．  
In one experiment，the researchers took all 200 items that Rico is supposed to know and divided them into 20 groups of 10 objects． 3 In the tests，Rico got 37 out of 40 commands right．As the dog couldn’t see anyone to get clues，the scientists believe Rico must understand the meanings of certain words．   
In another experiment，the scientists took one toy that Rico had never seen before and put it in a room with seven toys whose names the dog already knew． 4 .
The correct object was chosen in seven out of 10 tests．suggesting that the dog had worked out the answer by process of removing．A month 1ater，Rico remembered half of the new names，which is even more impressive．
5 Even if they do，they can’t talk back．Still．it wouldn’t hurt to sweet-talk your dog every now and then．You might just get a big，wet kiss in return!

A．The owner then told Rico to fetch the object，using a word the dog had never heard before．

B．Do dogs more understand us than some friends?

C．It’s hard to know if all dogs understand at least some of the words we say．

D．Be careful of what you say around your dog．

E．The dog also appears to be able to learn new words．
F．Then the owner told the dog to go and fetch one of the items．
G．Rico is thought to be smarter than the average dog．