充氧设备离航空器的距离不应小于()米。
A.2米
B.3米
C.4米
D.5米
参考答案:A
___ she was invited to the lecture made her very happy.
A.What
B.Because
C.When
D.That
下列那种物质不用于亚甲基兰测定()。
A.H2O
B.H2SO4
C.H2O2
D.HCl