For several billion years after the “Big Bang”, the earth was still just a cloud of dust. What it was to ______(36) was uncertain until between 4.5 and 3.8 billion years ago when the dust se
A plane crash in Western Russian killed Polish President Lech Kaczynski and the other 96 political and military officials on board on April 10. The accident has led to huge national mourning in
，当它完全水解时，可得到的产物有( )
结构。水解后得到：
、
、CH3COOH和CH3CH2COOH四种物质。