青少年正畸患者出现牙龈炎的几率为（）
A.10%～20%
B.20%～30%
C.30%～40%
D.40%～50%
E.50%以上
参考答案：E
—Excuse me. Is there a bank near here?
—No, ___. But you can find one in Yang Fang Road[ ]
A. there isn't
B. it isn't
C. they aren't
D. there is
胆囊结石的疼痛特点不包括()
A．多数为轻微隐痛
B．可有明显的胆绞能
C．常为夜间发作
D．疼痛向腹背呈束带状放射
E．疼痛与体位有关
