已知：a+b=9，ab=7，则a2+b2=（ ），（a-b）2=（ ）。
67；53
Basketball is so popular a game in the world that ______ people play it for fun and exercise. [ ]
A. million of
B. millions of
C. millions
D. two millions of
资产负债表左方列示负债和所有者权益各项目，右方列示资产各项目。( )
