更换新的监测试管时要更换“O”型密封圈是为了（），确保循环水回路和蒸汽回路完全隔离。
参考答案：保证密封的可靠性
All the organizations involved have sent urgent ________ to government, asking for extra funding. [ ]
A. appeals
B. replies
C. consultation
D. contracts
3,4-亚甲二氧基苯甲醛(胡椒醛)
