He has ________ in touch with his foreign friends for many years.
A:kept
B:had
C:keep
D:have
已婚的女性
已知圆的方程为x2+y2﹣8x+15=0,若直线y=kx+2上至少存在一点,使得以该点为圆心,半径为1的圆与圆C有公共点,则k的最小值是( )
番茄(西红柿)的外皮、果肉和其中的“筋络”分别属于哪种组织( )