As they had been  _____ our army for a week, the enemy had no choicebut to surrender (投降). [ ]

A. surrounding                                  

B. surrounded

C. surrounded by                              

D. surrounding with

剥脱性龈炎与下列哪项因素无关（）。

A.类天疱疮

B.扁平苔藓

C.天疱疮

D.红斑狼疮

E.白斑