洁净室空气的()和尘埃粒子数应定期监测。
参考答案:微生物数
The children all looked _____ at the broken model plane and felt quite _____.
A.sad, sad
B.sadly, sadly
C.sad, sadly
D.sadly, sad
大体积混凝土浇筑完毕后,后在( )内加以覆盖和浇水。
A.8 h
B.12 h
C.36 h
D.24 h