Why should a teacher habe a good command on Language?

Being an education student and part of my major to know the purposes of very topic that we are studying of. Now, here's one of our topic that I want to share my Personal Insight about it.

Language is the human capacity of acquiring and using communication in various types. There are many languages around us, and there are different languages that we are using in our entire life. Sometimes we are not aware where do language begin? Language comes from our vocal cord or mouth that produces sounds and instantly we initiate the sound and we get the meaning from the equivalent symbols that what we called "Letters". Human language may be form on Natural language, Sign language, and Written language. We as a human has only two capacity in acquiring language, first to develop was the First language which we develop starting from the age of infancy where the baby hears the sound that came out from the mouth of his parents, sisters, brothers and any part of the house member, that language called the "Dialect language" so the child try to speak what do other say. Second language is develop after knowing our first language, studying other language like English, Spanish, Japanese etc., is called second language regarding the numbers or mastered language.

       Another use of language it is a system of communication that enables human to cooperate. This definition stresses the social functions of language and the fact that human use it to express themselves and to manipulate objects in their environment. Good command of language is important for the teachers' ability in other him/her to teach effectively. Teacher need to familiarize to the language that she will using in her class probably the English language.Also the teacher needs to enhance her knowledge and comprehension in the language that the school curriculum requires.