Even though sign language has been used for thousands of years in one form or (1) ... , not much is known about its history. Some people believe that sign languages are not real languages, however, linguists (2) ... have studied them say that they are. The only difference is that instead of using speech or writing to express meaning, signers use their hands. As a (3) ... of fact, anything that can be expressed through spoken language can be expressed through sign language just as well. There is no (4) ... that learning sign language takes time and practice.