套利是期货投机的特殊方式,其丰富和发展了期货投机的内容,并使期货投机不仅仅局限于期货合约绝对价格的水平变化,而是更多地转向期货合约相对价格的水平变化。( )
参考答案:对
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.When I came into the classroom , I found him _______ with his study.
A.occupied
B.occupying
C.to be occupied
D.was occupied
世界人口最多的大洲是( )
A.亚洲
B.北美洲
C.欧洲
D.非洲