单根牙以_______处的牙周膜面积最大,多根牙以_______处的牙周膜面积最大,_______次之。
参考答案:牙颈部;根分叉区;牙颈部
The most popular store is at the end of the street. [ ]
A. clothing
B. clothes
C. cloth
D. A and B
Paul is Year 6 Star School in Shanghai.[ ]
A. in; on
B. at; in
C. at; at
D. in; at