A、<span style=";font-family:宋体;font-size:14px">一对一 </span></p><p></p>
B、<span style=";font-family:宋体;font-size:14px">一对多</span></p><p></p>
C、<span style=";font-family:宋体;font-size:14px">多对一</span></p><p></p>
D、<span style=";font-family:宋体;font-size:14px">多对多</span></p><p></p>