Joan likes playing _          guitar, but John likes playing_         soccer.            [ ]

A. the;/      

B. /; the          

C. the; the        

D. /;/

牙龈边缘呈蚕蚀状缺损，坏死组织为腐肉，表面覆盖假膜，伴严重口臭。镜下见密集的炎症及组织坏死区。龈沟液涂片可见梭形杆菌。该疾病可能是

A．青春期龈炎

B．浆细胞龈炎

C．急性坏死性溃疡性龈炎

D．剥脱性龈病损

E．药物性龈炎