我装置要求氢纯度为(),CO+CO2含量<()ppm,中变出口CO<()。
参考答案:99.9%、20、3
--- You look very tired. _____ at all last night?
--- No, not really. I’m tired out now.
A.Do you sleep
B.Were you sleeping
C.Did you sleep
D.Had you slept
下列关于中期妊娠水囊引产错误的是()
A.机械刺激促进前列腺素合成与释放
B.禁用于瘢痕子宫
C.适用于利凡诺引产禁忌证
D.感染率较其他方法高
E.应被广泛应用