下列物质中，作为燃料时对空气没有污染的是( )
A．原油
B．氢气
C．汽油
D．煤
答案：B
氢气燃烧产物为水，无污染。
The boss suggested to Jessica strongly that she should have a good time, but didn’t help.
A．which
B．she
C．she
D．it
OpenGL
