辨认主题句
Read the following paragraph and choose the best topic sentence from the four options that follow.
    From the moment Professor Sy Kee entered the class, we knew he would be dynamic and interesting. He walked in briskly; greeted the class in a clear, magnetic voice; and made us all feel comfortable. Professor Sally Forth is also an example of a good teacher. Her lectures are always carefully prepared, yet she affords every student an opportunity to join in class discussion. Even when a few students try to dominate the discussion, she politely, yet firmly, invites comments from even the most reluctant. But perhaps the most outstanding example of a good teacher is Dr. Frank N. Stein, who is always ready to meet with any of his students, and even goes as far as giving us his home phone number in case we have any problems with the assignments. These teachers, and others like them, are readily recognizable as good teachers.