被中止的事务对数据库所做的任何改变必须撤销，这称为事务的______。
参考答案：撤销或回滚或ROLLBACK或UNDO或Abort
We had worked only one hour it began to rain so heavily that we had to put up our tent.[ ]
A. before
B. when
C. after
D. until
该患者可能的诊断的是
A．自发性气胸
B．支气管哮喘
C．急性左心衰竭
D．气管异物
E．肺气肿
