可燃性粉尘的爆炸极限是以在混合物中所占体积的()比来表示的。
参考答案:质量
女、40岁。主诉右下后牙遇冷热敏感。刺激去除后,痛短暂持续,但无自发痛。检查发现右下第一磨牙面深龋,探诊敏感,但未发现穿髓,叩诊(-),备洞过程中极敏感。
应与其鉴别的牙病是()
A.牙隐裂
B.牙髓坏死
C.残髓炎
D.慢性闭锁性牙髓炎
E.慢性开放性牙髓炎
Over the past decades, sea ice _______ in the Arctic as a result of global warming. [ ]
A. had decreased
B. decreased
C. has been decreasing
D. is decreasing