上课铃声未响，同学们一个个涌进教室，由于天色异常，大家好奇地趴在窗台上往外看，纳闷不知发生了什么事。
Bell was not ringing in class, the students into the classroom one by one, because it was abnormal, you lie prone on the windowsill curiously looked out, wondering I don't know what had happened.
youdao