用提升F皮碗式堵塞器试压前，应保证试压管柱的水眼畅通，以防上提时套管内拔活塞，造成（）挤扁。
A、试压管柱
B、油管
C、套管
参考答案：C
Here's a new toy for you. Happy Children's Day! [ ]
A. Not at all
B. No, thank you.
C. Thank you very much.
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