I ______ have been more than six years old when the accident happened.
| A．shouldn’t | B．couldn’t | C．mustn’t | D．needn’t |
The excellent student, _______ abroad for many years, is on the way back to her own country.
| A．to study | B．studying | C．to have studied | D．having studied |
The student has the _______ for acting, but she needs training if she wants to be a top actress.
| A．document | B．potential | C．equipment | D．presentation |
We should try to do as many _______ things for the environment as we can.
| A．adaptable | B．beneficial | C．appealing | D．accessible |
He is said _______ for the International Criminal Police Organization for many years.
| A．to working | B．to work | C．to have worked | D．working |
He was sent to Australia _______ when he was ten years old.
| A．to be educated | B．to educate | C．educating | D．to be educating |