应用活动管柱解除砂卡时，每次活动10～20min应稍停一段时间，以防管柱疲劳而断脱。
参考答案：对
Father ____ that we four brothers try our best to help our uncle ___ everything he had done for us.
A．suggested; in return for
B．hoped; in exchange for
C．wished; in terms of
D．supposed; in turn
降低常压炉出口温度，其他操作条件不做调整，则（）。
A.常压塔顶温度降低
B.常压塔顶产品收率上升
C.常压塔进料汽化率不变
D.常压塔顶产品收率下降
