MH 370 which held 239 people disappeared_________ the early morning of March 8th , 2014 .
A:on
B:in
C:at
如图,沿直线AD折叠,△ACD与△ABD重合,若∠B=58°,则∠CAD= ____度.
物质在”空气或氧气中”发生变化,下列叙述不正确的是( )