题目

实数x、y满足x2+y2-6x+4y+9=0,则的最大值等于__________________. 答案：2+解析：圆(x-3)2+(y+2)2=22,圆心（3，-2）与（0，-1）的距离为：d=,d+r=+2.Hi, everyone．Let me introduce Mr. and Mrs. Smith—    1  English teachers to you．Mr. and Mrs. Smith    2    from England．They     3     English very well in our school． Mrs. Smith likes     4     books and     5    music．Now she can sing some Chinese songs．      Mr. Smith likes playing football．He often plays it    6     his Chinese students．Mr. and Mrs. Smith have two     7    ,a son and a daughter．They are students．      Mr. Smith has a brother．His name is Bill．He   8    with Mr. and Mrs. Smith．He is a singer．He can' t speak lots of Chinese,  9   he can play     10    piano very well． 1．A．we                  B．our                C．your 2．A．comes              B．is               C．come 3．A．teach               B．teaches            C．learn 4．A．read                B．to reading          C．reading 5．A．listening             B．listening to         C．to listeninging 6．A．and                B．to               C．with 7．A．children              B．childs               C．childrens 8．A．live                 B．lives               D．can lives 9．A．and                 B．but                C．so 10．A．the                B．a                 C．/