1.The boy does not know how (use)............. a computer.
2.I am nervous about (make)........... friends with her.
3.Editors are responsible for (write)......... editorials.
4.It is interesting (study).........the history of today's motion-picture industry.
5.By the end of 1992,over 500 radio stations had begun (broadcast).............. around the United States.
6.The first station was created by radio equipment companies in order (develop)............ a market for their products.