球体截交线投影可能是圆、椭圆或（）。
A、直线
B、三角形
C、四边形
D、多边形
参考答案：A
现在有相同浓度的CH3COONa和NaClO溶液，两溶液中阴离子浓度的大小关系正确的是
A．前者大于后者
B．后者大于前者
C．两者相等
D．无法确定
When I saw James, he ________ chess with his grandfather in the garden.[ ]
A) plays
B) played
C) was playing
D) had played
