— Why! I _____ get you on the phone.
— We ______ basketball on the playground when you phoned.
| A．didn't; must be playing |
| B．couldn't; must be playing |
| C．couldn't; must have played |
| D．didn't; must have been playing |
He often makes his sister .
| A．cry | B．to cry | C．crying | D．cried |
I want to buy is a book.
| A．How | B．What | C．That | D．Who |
Either you or Igoing to the teacher’s office after class.
| A．are | B．is | C．am | D．will |
Travelling a good way to learn about the world.
| A．is | B．are | C．have | D．has |
It is difficult a best friend.
| A．to find | B．finding | C．find | D．to be found |