In the future I am going to be an inventor．This winter holiday I don't want to go out to play．I want to ____something myself at home．I want to help old people____a light and folding bike．They ride it to the ____，then folding it and put it in the bag．After buying some things they can ride it and carry their things to go ____．They are not tired．I think if they see it，they must be very ____．