A:8种
B:10种
C:13种
D:16种
①在同一平面内,a、b、c是直线,a∥b,b∥c,则a∥c
②在同一平面内,a、b、c是直线,a⊥b,b⊥c,则a⊥c
③在同一平面内,a、b、c是直线,a∥b,a⊥c,则b⊥c
④在同一平面内,a、b、c是直线,a⊥b,b⊥c,则a∥c.
—I have difficulty working out the problem by myself. Could you help me?
—_____________.
中国与东南亚陆地相邻的一组国家是( )