A:职业平等观
B:树立自主择业观
C:竞争就业观
D:多种方式就业观
—_________ is your science teacher?
—My science teacher is at home.
若圆C:x2+y2+2x-4y+3=0关于直线2ax+by+6=0对称,则由点(a,b)向圆所作的切线长的最小值是( )