Being afraid of making mistakes, the little boy __________ answer his teacher's questions.
With more forests being destroyed, huge quantities of good earth ______ each year.
________ in a poor family, he can’t afford to go to school.
According to my father, movies, such as the one you talked about yesterday, _____ not worth seeing.
The president spoke at the business meeting for nearly an hour without ______ his notes.
E-mail, as well as the telephone, ___________ an important part in daily communication.