题目

— I don’t have a partner to practice English ______.— Why not join an English language club to practice ______?A．/; speaking    B．with; speaking C．/; to speak    D．with; to speak 答案：B在△ABC中，内角A，B，C对边的边长分别是a，b，c，且满足a2+b2=ab+4，C=π3．（1）A≠π2时，若sinC+sin（B-A）=2sin2A，求△ABC的面积；（2）求△ABC的面积等于3的一个充要条件．