向一无色溶液中滴加氯化钡溶液时,有白色沉淀生成,此沉淀不溶于稀硝酸,则该溶液中一定有大量的( )
A:Ag+和CO32﹣
B:Ag+或SO42﹣
C:SO42﹣
D:Ag+
——All the teachers went on a trip to Hainan yesterday Mr. White. Why?——Because he was too busy a new novel to travel.
设F1、F2是椭圆E:x2a2+y2b2=1a>b>0的左、右焦点,P为直线x=3a2上一点,△F2PF1是底角为30°的等腰三角形,则E的离心率为( )