完形填空。阅读下面短文，掌握其大意，从每题所给的A、B、C、D四个选项中，选出最佳选项。
Even though it was only October, my students were already whispering about Christmas plans. With each passing day everyone became more anxious, waiting for the final school bell. Upon its 1 everyone would run for their coats and go home, everyone except David
