80286有24条地址线，可寻址空间为（）
A.640kB
B.64kB
C.1MB
D.16MB
参考答案：D
--- How much homework has your cousin finished?
--- _______ at all. He has sat there the whole morning, doing _______.
A．None; nothing
B．Nothing; none
C．No one; nothing
D．None; none
第二次鸦片战争以后，俄国先后割占了中国约150万平方公里的土地。[ ]
