—
A:Thank you.
B:That's fine.
C:Don't worry.
D:I think it helps.
A.CO和CO2 B.CO和H2 C.H2和O2 D.____.
用镁铝合金制作的窗框、卷帘门、防护栏等物品轻巧、美观、耐用.与上述这些特点无关的镁铝合金的性质是( )