If _____ for an explanation for an advanced camera, I would certainly find it difficult.
| A．to be asked | B．being asked | C．asking | D．asked |
________about the student，the teacher called his parents to find out why he was so often absent from class.
| A．Concerning | B．Concern |
| C．Concerned | D．To concern |
This is neither the time nor the place to play.Let’s________and attend to the business in hand.
| A．come up | B．turn off |
| C．settle down | D．cut in |
For years the government of that country________their responsibility when it comes to the mentally ill.
| A．ignored | B．is ignoring |
| C．has ignored | D．ignores |
Teachers’ Day is a time to be________to all teachers who deserve special recognition.
| A．available | B．grateful |
| C．generous | D．ridiculous |
Air pollution is getting more and more serious，so we must take action________it is too late.
| A．before | B．after |
| C．until | D．when |