由于地层产油的综合含水上升，使用化学药品应是：（） ["按原比例加药","根据综合含水上升情况调整","增加加药浓度"]
社会分层
在履行合同过程中，发生不可抗力事件使一方或双方无法继续履行合同时，不能解除合同。
单相异步电动机启动一般有电阻分相启动、电容分相启动和（）。 ["单相启动","单三相启动","多极启动","罩极启动"]
The EMP table has some discrepancy in data entry with a particular employee ID. You execute the query as shown in the Exhibit to retrieve all versions of the row that exist between two SCNs.View the Exhibit. Which two statements about the results of the query shown in the Exhibit are correct? （）(Choose two.) [" The LAST_SCN value in the first row is NULL, which means that the versions of the row still exist at SCN 6636300."," The LAST_SCN value in the second row in NULL, which means that the version of the row still exists at SCN 6636300."," The LAST_SCN value in the third row is 6636280, which means that the version of row exists above SCN 6636280."," The LAST_SCN value in the second row is NULL, which means that the version of the row no longer exists because it was deleted."]
风景名胜
