慢性牙周炎患者的主诉症状通常为
A．牙齿松动
B．咀嚼无力
C．咀嚼疼痛
D．牙周溢脓
E．以上均可能
参考答案：E
Never should we forget the war and sufferings _____ caused to the people.
A．it
B．which
C．that
D．what
有庭院的单位要检查是否杂草丛生，一但植物过高或过于茂盛。容易成为歹徒（）之处。
