根据下列材料回答第15题：Dr. William C Stokoe, Jr, was the chairman of the English Department at Gallaudet University. He saw the way deaf people communicated and was extremely __21__. He was a hearing person, and signs of the deaf were totally new to him. Dr. Stokoe decided to propose a study of sign language. Many other teachers were not interested, and though Dr. Stokoe was __22__ to think about studying sign language. Even deaf teachers were not very interested in the project. However, Dr. Stokoe did not give up. __23__, he started the Linguistics Research Program in 1957. Stokoe and his two deaf assistants, worked __24__ this project during the summer and after school. The three __25__ made films of deaf people signing. The deaf people in the film did not understand __26__ the research about and were just trying to be nice to Dr. Stokoe. Many people thought the whole project was silly, but __27__ agreed with Dr. Stokoe in order to please him. Stokoe and his __28__ studied the films of signing. They __29__ the films and try to see patterns in the signs. The results of the research were __30__: the signs used by all of the signers __31__ certain linguistic rules. Dr. Stokoe was the first linguist to test American Sign Language __32__ a real language. He published the __33__ in 1960, but not many people paid attention to the study. Dr. Stokoe was still __34__ —he was the only linguist who __35__ that sign language was more than gestures. He knew it was a language of its own and not just another form of English.{TS}填入（21）处的最佳答案是（）。