4.Would you please add some salt to the soup?It's not s_______ enough.

 3.Someone must have left the door open by m________.

 2.Potato chips are c________.Most children like to eat them.

1.In high temperatures,milk goes s_______ very quickly.

 (    )5.A Disneyland Park _______ in Shanghai Pudong New Area in the near future.

       A.completes                   B.has completed

       C.will complete               D.will be completed

 (    )4.The food smells _______. We can't eat it. Please throw it away.

       A.salty                      B.delicious

       C.sweet                      D.sour

（2014 厦门） It seems very natural that if you have two dollars and add two dollars to them, you have four dollars. But do you know it took man millions of years to be able to think this way? In fact , one of the most difficult things to teach children is the idea of numbers.

    In ancient times , when a man wanted to tell how many animals he owned, he had no system（体系）of numbers to use. He put a stone or pebble into a bag for each animal. The more animals,the more stones or pebbles he had. It may explain why the word “calculate” comes from the Latin word “calculus” which means “stone”.

    Later on , man used tally marks to count. People would just scratch（划下）a line or tally mark for each object they wanted to count, but they had no word to tell the number.

    The next step in the development of the number system was probably to use fingers. Again we have word that goes back to this. The word “digit” comes form the Latin word “digitus”. It means “finger”! And the fact that we have 10 fingers led to the general use of 10 in the system of numbers.

    The number system we use today was invented by the Hindus in India thousands of the years ago and was brought to Europe during 8th to 11th century by Arab traders. In this system all numbers are written with the nine digits 1,2,3,4,5,6,7,8,9 and zero. It is decimal system（十进制）, that is, it is built on the base of 10.

1. Man first used ______ for counting.

  A.a line or tally mark      B. a stone or pebble      C. fingers

2. If A and B each scratched three lines for their own objects to be counted, they      would probably have ______ objects in all.

   A. three          B. six              C. nine

3.The two Latin words in the text are _______ .

  A. calculus and stone      

  B. digitus and finger          

  C. calculus and digitus

4.  _______invented the number system we use today.

  A. The Hindus in India     B. Europeans      C. Arab traders

5. There are ________ steps in the development of the counting system.

  A. two          B. four             C. five

 5.The boy ________(think) he was wrong and said sorry to his parents.

 4.Do you know how this kind of food _________(invent)?

 3.The soup is a little too _______(salt).Could you add some water to it?