治疗慢性再障时应首选()
A．造血干细胞移植
B．联合应用造血刺激因子
C．环孢素A+雄性激素
D．山莨菪碱+一叶秋碱
E．雄性激素
参考答案：C
牙菌斑是指（）。
A.软而未钙化的牙面沉积物
B.牙面上一种细菌性生物膜
C.龈缘处软而粘的沉积物
D.牙面上矿化的细菌性群体
E.牙面上细菌性群体
The fire spread through the hotel very quickly but everyone _____ get out. [ ]
A. had to
B. could
C. was able to
D. could
