正压式空气呼吸器气瓶阀完整、密封、灵活,气源压力正常,高压泄漏检查、低压报警哨测试正常低于≤()Mpa时报警。
参考答案:5
Thanks for _____ care of my dog when I was away. [ ]
A. take
B. took
C. taking
D. takes
呼吸系统感染最常见的病原体是:()
A.原虫
B.病毒
C.细菌
D.支原体
E.寄生虫