Such problems （ ） air pollution and traffic jams are becoming more and more serious in some big cities.

（ ） comes back first is supposed to win the prize.

The kidney transplant operation was _____ complicated, so the operating team had to take special care to ensure its success.

John Smith, a diligent student, never refuses to （ ） more responsibilities that are assigned to him.

She is very （ ） to his ugly appearance.

Her （ ） to the job left her with very little free time．

It was not known （ ） he had said during the interview.

Ted, （ ） yourself and don’t get your coat dirty again, or you will get into trouble!

（ ） when she started complaining.

Only when （ ） in the afternoon （ ） able to leave.

We don’t doubt _____ he can do a good job， concerning his experience.

_____, the professor is still trying to learn a new language.