普通手术室空气消毒可以采用下列哪种方法消毒:().
A.紫外线照射
B.紫外线循环风空气消毒机或静电吸附式空气消毒机
C.消毒液擦拭消毒
D.消毒液喷洒
参考答案:B
—Does Liu Hui serve in the army?
—No, but he ________ in the army for three years.
A.served
B.has served
C.is serving
D.would serve
基坑土方开挖的原则是( )。
A.先撑后挖,分层开挖
B.先挖后撑,分层开挖
C.先撑后挖,分段开挖
D.先挖后撑,分段开挖