压力式除氧器应采用全启式弹簧安全阀，且不少于（）只。
A.1
B.2
C.3
参考答案：B
It is what you do _________what you say that matters. [ ]
A. in place of
B. rather than
C. or rather
D. in spite of
获取核能有两条途径：重核的裂变和轻核的聚变．如图，甲图属于 ______变；乙图属于 ______变．太阳释放出的巨大能量来源于 ______变．
