Present at the historic meeting ________ many an official on Nov 7, of course President Xi Jinping and Ma Ying-jeou ________.
A:was; included
B:was; including
C:were; included
D:has been; included
θ是三角形的一个内角,且sinθ+cosθ=15,则方程x2sinθ+y2cosθ=1所表示的曲线为( ).