There are all kinds of machines. They  21  in many different ways. One kind of machine is called a computer. A computer can do many things. A computer can do math problems. People can also do math problems. But they cannot do it   22  a computer.
Computers remember things. Computers do   23  people tell them. People cannot remember as many things as computers. Computers help tell   24  the weather will   25  .Computers help fly rockets and spaceships.
These are   26  of ways computers are used. They are used in 27  ways. Some computers do just 28  things. Some computers can do a lot of things. There are  29  computers. There are big computers. There may be computers in your school. Do you   30  what they do?
【小题1】.

There are ________ people in the park.

1. A.
   thousands of
2. B.
   thousand of
3. C.
   two thousands
4. D.
   two thousands of

There are ________ people in our school.

1. A.
   two thousand
2. B.
   two thousands
3. C.
   thousand of
4. D.
   two thousands of

There are over two ________ workers in the company, and ________ young people want to work in it．

1. A.
   thousands; thousands
2. B.
   thousands; thousands of
3. C.
   thousand; thousands of
4. D.
   thousand; thousand of