四.閱讀測驗:選擇最佳的選項,以完成該空格.Language is the most important development in human history. However, little is known about the birth of language. Written records that are more than four thousand years old have been found, but scientists (科學家) agree that humans were speaking thousands of years before that. Today most of us learn to talk by the age of three, and for the rest of our lives, we rarely stop. Even while we are reading or just thinking, we are in a way "talking" to ourselves. Language is so much of part of human existence that we will be talking as long as we live on the earth
.47. How much do we know about the birth of language?
(A) Very much.  
(B)  A few years. 
(C) Very little. 
(D) Four thousand years.