Number sense is not the ability to count．It is the ability to recognize a 1 in number．Human beings are born with this ability． 2 , experiments show that many animals are, too．For example, many birds have good number sense．If a nest has four eggs and you remove one, the bird will not 3 ．However, if you remove two, the bird 4 leaves．This means that the bird knows the 5 between two and three．
Another interesting experiment showed a bird's 6 number sense．A man was trying to take a photo of a crow(乌鸦)that had a nest in a tower, but the crow always left when she saw him coming．The bird did not 7 until the man left the tower．The man had an 8 ．He took another man with him to the tower．One man left and the other stayed, but they did not 9 the bird．The crow stayed away until the second man left, too．The experiment was 10 with three men and then with four men．But the crow did not return to the nest until all the men were 11 ．It was not until five men went into the tower and only four left that they were 12 able to fool the crow．
How good is a human's number sense? It's not very good．For example, babies about fourteen months old almost always notice if something is taken away from a 13 group．But when the number goes beyond three or four, the children are 14 fooled．
It seems that number sense is something we have in common with many animals in this world, and that our human 15 is not much better than a crow's．
As my wife greeted me one evening, her voice came through the door,“Guess what?”
I always take a deep 1 on this very leading question．“What?”I asked．
“I just won a sales contest at work and the 2 is dinner for two at the new fancy restaurant down by the river-front!”
She was so 3 ．We knew the restaurant was extremely good．“See?I told you there would be a 4 for me to wear my new spring outfit,”she shyly reminded me．
“ 5 can play at that game,”I responded．“I will wear my gray suit, my Borsalino imported straw hat and a new silk tie．We will be well 6 ．”
It was early 7 and nearing dusk as the waiter took us to a table by a window, with a(n) 8 of the river．And the table was 9 set, with a smoke-gray tablecloth and bright colored napkins．
A delicious meal 10 in such an atmosphere should be remembered a long time．As it 11 , this will probably never be forgotten．
As the shadows lengthened, the 12 rocking by the riverbank, I murmured,“Why not take a walk?”
Hand in hand, we walked by the stores．People smiled and nodded．“I 13 realized there were so many 14 people as we have seen this evening, dear,”I observed．
“Probably your new straw hat or your 15 ,”she said．
After receiving many smiles, we 16 ourselves back at the restaurant, looking at ourselves in the 17 ．It was then that I saw the 18 for all the smiles．
Caught in the fly of my trousers and 19 down for all to see was a bright red 20 from the restaurant!
When I was a little girl, every Sunday my family of six would put on our best clothes and go to Sunday School and then church．The 1 in elementary school would all meet together to sing songs, and then later divide into 2 based on their ages．
One Easter Sunday, all the kids 3 with big eyes and big 4 about what the Easter Bunny(复活节小兔)had brought． 5 all of the kids shared their stories with 6 , one young boy , whom I shall call Bobby, sat 7 ．One of the teachers , noticing this, said to him, “And what did the Easter Bunny 8 you?”He replied, “My mom 9 the door by accident so the Easter Bunny couldn't get 10 because he hadn't got a key．”
This sounded like a 11 idea to all of us kids, so we kept on going with the stories．My mom knew the true story, 12 ．Bobby's mom was a single parent , and she suspected(怀疑)that they just couldn't 13 the Easter Bunny．
After Sunday School was over, everyone went off to 14 ．But my mom announced that we were going home 15 ．At home, she explained that to make Bobby feel 16 , we were going to pretend(假装)to be the Easter Bunny , make a basket of our candies for him and 17 it at church．We all donated(捐赠)some to the basket, and 18 back to church．There, mom hung the basket over the hanger(挂钩)and attached(附上)a(n) 19 ：
Dear Bobby,
I'm sorry I 20 your house last night．Happy Easter．
