简述批处理操作系统的作业调度和作业调度选择作业的必要条件。
参考答案：
Luckily, the poor boy had enough money _____ he could buy a train ticket.
A．by which
B．on which
C．with which
D．for which
混悬型气雾剂为
A．一相气雾剂
B．二相气雾剂
C．三相气雾剂
D．喷雾剂
E．吸入粉雾剂
