导体两端的电压为6V，通过它的电流是0.3A，则该导体的电阻是____ Ω；若导体两端电压变为12V，则通过它的电流为____ A；若将电路断开，该导体的电阻为____ Ω．

    Do you want to know what our life will be like in the future? Let's have a look. You may get a surprise.

    You will go to the kitchen when you are hungry. You will give orders to the kitchen robot. The robot will cook the food for you in a few minutes. Then it will bring it to you.

    In the kitchen you will find a special food machine. The food machine will tell you what your body needs. It will help you eat healthily. The food machine will be connected with(连接) the kitchen robot. The robot can get messages from the food machine.

    After having a meal, you can go to your home office. You will work at home and you don't need to go out to work any more.

    You will have a special information screen. You can get any information on the screen. When you receive a message from a friend in America, your information screen will be turned on automatically(自动地).Your friend's face appears on the screen. Then you can talk to your friend easily.