Many people worry that air pollution might changes in the weather around the world.
| A．add to | B．lead to | C．turn to | D．belong to |
His speech is easy _____.
| A．to follow | B．to be followed | C．for being followed | D．to follow it |
Physics is difficult ____.
| A．to be learned | B．to learn | C．to be learning | D．to be learn |
English is too hard __ for some people.
| A．to be master | B．to master it | C．to master | D．master |
It is necessary ___ the magazines in time.
| A．to us to return | B．for us to return | C．to us returning | D．that we had returned |
It is careless ___ such a mistake.
| A．of you to make | B．of your making | C．for you to make | D．for your making |