Choose the correct option to fill in the blanks. 1) They _...

“It has been said that teachers who have been teaching for twenty years may be divided into two categories: those with twenty years' experience and those with one year's experience repeated twenty times. In other words, sheer time on the job does not ensure fruitful experience and professional progress. (...) A teacher can and should advance in professional expertise and knowledge throughout his or her career, and such advances do not depend on formal courses or external input. You have within your own teaching routine the main tools for personal progress: your own experience and your reflections on it, interaction with other teachers in your institution. Teacher development takes place when teachers, working as individuals or in a group, consciously take advantage of such resources to forward their own professional learning. Ongoing teacher development is important not only for your own sense of progress and professional advancement; in some situations it may even make a crucial difference between survival and dropping out.” (A Course in Language Teaching, by Penny Ur, p. 317/18. Adapted)