It 's unacceptable for a mother to leave her child ________to play computer games.
A alone B．lonely C．lone D．loneliness
—What do you think makes him so sad?
— __________ the exam.
| A．He failed | B．He failing |
| C．His failing | D．To have failed |
Ladies and gentlemen, please fasten your seat belts. The plane __________.
| A．takes off | B．is taking off |
| C．has taken off | D．took off |
When delivering the speech, you can __________ your note if necessary.
| A．refer to | B．come across |
| C．look after | D．watch out |
—I'm going to travel to America. Would you consider telling me about your experiences there?
— __________. Let's discuss it over dinner.
| A．That's all right | B．By all means |
| C．Go ahead | D．it just depends |
Not until he left his home __________ to know how important the family was for him.
| A．did he begin | B．had he begun |
| C．he began | D．he has begun |