王海学了几年英语，由于没有经常进行听说训练，遇到外宾时，他听不懂，也表达不清。今后他要试用各种技巧和方法来提高英语水平。要求用第三人称叙述，词数控制在100～120词左右。

A. by far
B. at random
C. in number
D. out of order

A. advertisers are interested in experimenting with new ideas
B. it is still at an early stage of development, compared with the radio
C. the programs have to be developed in the interests of the sponsors for economic reasons
D. it is controlled by radio companies