When television first began to expand, very few of the people who had become famous as radio commentators【31】 effective on television. Some of the difficulties they experienced when they were trying to【32】themselves to the new medium【33】 When working【34】 radio for example, they had become【35】 to seeing on behalf of the listener. This art of seeing for others means that the commentator had to be very good at taling.【36】 all he has to be able to create a continuous sequence of visual images which add meaning to the sounds which the listener hears. In the case of television, however, the commentator sees everything with the viewer. His role,【37】is completely different. He is there to make sure that the viewer does not miss some point of interest, to help him focus on particular things, and 【38】 the images on the television screen. Unlike his radio colleague, he【39】 know the value of silence and how to use it at those moments【40】 the pictures speak for themselves.
(31)

A. were able to be equally
B. were able to be equal
C. were able being equally
D. were able to be equal