根据短文内容，判断正误。正确填(A)错误填(B)。
What would the future life be like? I think we can travel faster and safer around the world and into space. Maybe one day we can work in Beijing, sleep in Chengdu and visit the moon for a holiday.
We will have new energy(能源) that doesn’t make pollution. Possibly, people will find ways to use cleaner things, such as sea water, to make energy without polluting the earth.
We will have machines that can copy everything in the future. Put a cake on the machine and it makes a new one. Of the machine is like a fax-machine, we can send food and presents to our friends easily.
We will have clever robots that work for us, and the robots can bring us useful things and take away our trash. Now we have to press a key or type a word to make a machine work. But in the future, if we think of something, the machine can make it for us. The machine can understand our ideas.
We can go into computer games and films, and everything will feel real. We can make our homes like forests or sunny beaches or anything we want. Maybe, one day we can collect our dreams and put our dreams on DVDs
金属的活动性由强到弱的顺序是 （ ） 