A:①②
B:②③
C:③④
D:①④
如图,将矩形ABCD沿对角线BD折叠,使点C落在点E处,BE与AD交于点F.
The upset mother thought to herself, “If only I ______ what's going on in my little boy's head right now.”
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中国历史上第一个奴隶制国家是( )