Backpacks are convenient. They can hold your books, your lunch and clothes. They leave your hands free to do other things, especially when you are carrying something heavy.
　　Now inventors from the US have invented a backpack that makes electricity while its wearer walks.
　　In the new backpack, the metal pack frame is attached to the body but the carrying part hangs from springs attached to the frame. The springs connect with a special green rod. As you walk, the rod moves up and down. It turns a gear(齿轮)on a generator(电动机)that makes electricity.
　　The special backpack could be useful for soldiers, scientists and hikers who carry heavy things. These people often depend on battery powered items such as GPS and night vision glasses to get around. Since the pack can make its own electricity, users don't need to carry batteries.
　　For the rest of us, the new backpack could make it possible to walk, play video games, watch TV and listen to music at the same time. The invention has not been on the market yet, but if you do get one some day, just make sure to have a try!
1). The underlined word “backpack” means a kind of bag which can be carried______.
A. on one's head B. in one’s pocket
C. in one’s hands D. on one’s back
2). What is the first passage mainly about?
A. The cost of backpacks. B. The convenience of backpacks.
C. The problem of backpacks. D. The place to buy a new backpack.
3). Which is NOT true about the new backpack?
A. You can buy one in the shops or markets now.
B. Your hands will be free to do other things when carrying it.
C. It would be especially useful when carrying something heavy.
D. You will be able to put your books, your lunch and clothes in it.
4). Which part of the backpack might possibly produce electricity?
A. The springs. B. The carrying part.
C. The generator. D. The special rod.
5). According to the passage, ______often carry heavy things to get around and
may find the backpacks convenient.
A. actors and scientists B. soldiers and hikers
C. drivers and soldiers D. hikers and shop assistants