在各组中

（1）9a²x和9ax²；（2）xy²和﹣xy²；（3）2a²b和3a²b；（4）a2和2a；（5）ax2y和axy2；（6）4x2y和﹣yx2，是同类项的共有 [ ]

A．2组

B．3组

C．4组

D．5组

The foreign friends you referred to ________ looking forward to ________ around our university.[      ]

A．are; being shown  

B．being; being shown

C．being; showing  

D．are; be shown