某内燃机混合加热理想循环,从外界吸热1000kJ/kg,向外界放热400kJ/kg,其热效率为()。
A.0.3
B.0.4
C.0.6
D.4
参考答案:C
There are a great many books in the store, _____ some are useful to us. [ ]
A. of them
B. in which
C. of which
D. in them
患者,女性,37岁,胃溃疡,胃大部切除术。术后24h内,护士应重点观察
A.胃管引流液与血压变化B.有无尿潴留C.生命体征变化D.切口感染E.咳嗽与肺部并发症