4 Fill the gaps with can, can't, could, couldn't, will be able to or won't be able to.
- In the past, robots________ teach in classes, but they can now.
- Robots can't talk now. In 2030, they________talk to people.
- Mr Van______ run very fast when he was young. Now he_______ .
- In 2030, robots will be able to talk to us, but they ____ do more complicated things.
- My little sister is very clever. She________ already read some words.
4 Fill the gaps with can, can't, could, couldn't, will be able to or won't be able to.