It’s not difficult ________ the problem.
| A．for him solve | B．for him to solve | C．of him solving | D．of him to solve |
Teachers’ job is ______ the students learn well.
| A．helping | B．help | C．to help | D．helped |
Students ought ______ the truth.
| A．told | B．tell | C．telling | D．to tell |
I can’t stand _____ for you so long.
| A．to wait | B．waiting | C．waits | D．waited |
There is _____ pollution in the world. We must stop it.
| A．much too | B．too many | C．many too | D．too much |
The cleaners must prevent the street ______.
| A．getting dirty | B．from dirty | C．from get dirty | D．from getting dirty |